Scanning Image Processing Research Articles

Development of an automated urban heritage monitoring tool: Between a techno-fix and fallacy

The preservation of urban heritage is one of the main challenges for contemporary society and an important task for governments. The administration of urban heritage preservation (UHP) requires effective methods, as well as sufficient material and human resources. The administrative practice of UHP is embedded in the relevant regulatory framework, which comprises legislative and normative acts at municipal, national, and international levels. The scale and range of heritage objects to be monitored, the complex statutory basis of the regulatory framework, and the traditionally low human and material resources of city administrations all contribute to the ineffectiveness of UHP practice in the UNESCO World Heritage Site of Vilnius.Advances in technologies such as 3D spatial scanning and AI-based image processing offer the promise of a technological fix to the ineffective administrative practice. In this paper, we present a grounded design study aimed at developing a technology prototype for an automated urban heritage risk monitoring tool. Originally conceived as a techno-fix to the inefficiency of administrative practice, the prototype development reveals tensions and stumbling blocks within digitalisation efforts. Using the analytical lens of the Trifecta model of IT-based regulation, the case study examines the interaction between technological and administrative domains in shaping technology design choices.Based on this case study, we critique the notion that IT is perceived as capable of providing “techno-fix” solutions to tasks requiring reflective human decision-making, especially when such solutions are expected to be effective without first redesigning the entire organisational system. The paper concludes with a discussion on the limits of automating administrative practices and identifies specific avenues for further research into the digitalisation of urban heritage preservation.

Functional description of fiber orientation in paperboard based on orientation tensors resulting from μ-CT scans

Modern μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}-CT scans offer non-destructive three-dimensional microstructure analysis of various materials. Despite small density contrasts, this technology also accurately captures the complex network structure of paper and paperboard. It provides detailed insight into the fiber orientation distribution in paper, which was previously unattainable with existing measurement methods. The image analysis results are applicable for numerical fiber network models, and simulations based on these models can significantly improve our understanding of the microstructural influence on macrostructural paper properties, such as strength, stiffness, and curl tendency. This work presents a new method for investigating the microstructural fiber orientation in paperboard. Orientation tensors obtained from μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}-CT scan image processing are extracted and evaluated. Based on the direction of the orientation tensor’s first eigenvector, the fiber orientation distribution is determined and then approximated by periodic and non-periodic probability density functions (PDFs). In this study, 40 commercial paperboard samples, each consisting of three plies, were analyzed. From a given set of commonly used PDFs, the best fitting ones have been identified based on their original location in the paper roll and on their ply. It was found that the von Mises PDF provided the most accurate representation of fiber orientation distribution in the middle ply, while the Elliptical PDF was the most suitable for the outer plies. Moreover, a more pronounced fiber orientation anisotropy was observed at the edges of the paper roll than in its center. The best PDFs and their function parameters are provided to allow for direct usage in numerical microstructure models of paperboard, thus enhancing their representativeness.

Damage evolution in asphalt mixtures based on in-situ CT scanning

A novel approach utilizing in-situ Computed Tomography (CT) scanning and digital image processing techniques was developed to overcome the limitations of traditional CT image analysis in studying microcrack evolution in asphalt mixtures. Two types of graded asphalt mixtures (continuous gradation/AC and intermittent gradation/SMA) were scanned in-situ to capture internal structural changes. Digital image processing distinguished primary voids from cracks and extracted crack evolution. Multivariate regression analysis linked crack parameters to compressive strain. The study found that crack evolution during uniaxial compression in asphalt mixtures can be divided into densification, linear elastic deformation, and nonlinear failure stages. As load increases, the number, volume, and void percentage occupied by cracks rise, peak, and then decrease due to merging and engulfing after the ultimate load. The skeletal structure of cracks was obtained, and a damage evolution equation was established, linking crack parameters to damage evolution. Crack tortuosity was used to characterize the resistance effect of different gradations on crack propagation. This methodology provides new insights and technical support for studying damage evolution and understanding the failure mechanisms of asphalt mixtures.

Experimental and statistical study on sound absorption coefficient of porous asphalt concrete considering mesoscopic pore parameters

Porous asphalt concrete (PAC) has attracted significant attention in the road industry due to its excellent noise reduction capabilities. However, clogging in PAC decreases its sound absorption performance, as mesoscopic pore parameters play a crucial role in influencing PAC’s sound absorption abilities. To further investigate the influence of mesoscopic pore parameters on the sound absorption performance of PAC, CT scanning and digital image processing technology were employed. The principal component analysis method was employed to determine the weighting of the influence of mesoscopic pore parameters on the sound absorption coefficient. The correlation between different pore parameters and the sound absorption coefficient of PAC specimens was analyzed. The results showed that the minimum Feret diameter has the most significant effect on the sound absorption performance of PAC, while the concavity and the length-short axis ratio have the least impact. The correlation between mesoscopic pore parameters and sound absorption coefficients was found to be inconsistent before and after clogging. Mesoscopic pore parameters that were positively correlated with sound absorption coefficients before clogging turned negatively correlated after clogging. Connected large pores and smooth regular pore structure enhance the sound absorption performance of PAC, but clogging disrupts this structure, resulting in a decrease in sound absorption performance.

Permeability evolution of fractured coal subject to confining stress and true triaxial stress loading: experiment and mathematical model

The accurate elucidation and prediction of coal permeability evolution under stress loading conditions are crucial for coalbed methane production. In this study, flow experiments were conducted on six cylindrical coal samples and four cubic coal samples under both confining and true triaxial stress loading conditions, respectively. The structure and characteristic parameters of the fractures inside each coal sample were obtained using the computed tomography scanning system and image processing technologies. The coal permeability under both types of loading processes was calculated through the transient pulse method. A mathematical model was developed to assess the evolution of coal permeability under true triaxial loading based on the current true triaxial permeability model and fractal theory. The results revealed that during the confining pressure loading, the coal permeability decreased exponentially with effective stress and was effectively described using the SD model. Additionally, the coal permeability initially rapidly decreased, followed by a gradual decrease, and eventually stabilized at a constant value. Particularly, during the first three loading steps, the fracture aperture and corresponding permeability of the six cylindrical coal samples decreased by ∼51.79%–57.83% and ∼38.06%–42.12%, respectively. However, during the final three loading steps, the fracture aperture and corresponding permeability of the six coal samples decreased by ∼18.26%–23.08% and ∼22.15%–26.93%, respectively. Moreover, owing to the various crossing angles of complex fracture networks with each principal stress, the effect of each principal stress on the coal permeability evolution was highly anisotropic during triaxial stress loading. Particularly, the permeability of the ST1 sample decreased by 43.08%, 14.84%, and 42.08% during the loading of each principal stress. Similarly, the permeability of the ST2 sample decreased by ∼65.74%, 14.29%, and 19.97%. The permeability reductions for the ST3 sample were ∼34.03%, 55.85%, and 10.12%, while those for the ST4 sample were ∼35.97%, 46.51%, and 17.52%. The SD model failed to describe these anisotropic effects. Compared with the SD model, the improved model, based on the current true triaxial permeability model and fractal theory, effectively described the anisotropic effect of each principal stress on the permeability of coal samples with complex fracture networks under triaxial stress conditions.

Shape characteristics and crushed law of deep sandstone impact crushed blocks based on digital reconstruction

In order to study the shape characteristics and crushing law of deep sandstone impact crushed blocks under different impact loads. In this paper, Split Hopkinson pressure bar (SHPB) tests were conducted on sandstone specimens under different impact loads. A digital three-dimensional model of the crushed blocks was established by combining 3D scanning and digital image processing technology, and the shape parameters of the crushed blocks were statistically analyzed based on Image-Pro plus (IPP) software. The results show that with the increase of the impact loads, the overall shape of the rock becomes irregular, and the angularity and surface texture are more obvious. With the increase of the impact loads, the degree of fragmentation of the specimen also becomes larger, which is manifested by the increase of the number of blocks and the decrease of particle size. The specific surface area of the crushed block is negatively correlated with the particle size, and the relationship between the two is basically a power function y=25.04*x−1.12, the degree of discreteness of the particle size distribution of the crushed block is positively correlated with the loads. With the increase of impact loads and input energy, the shape of the block is gradually enriched after the specimen is broken, and the broken form of the specimen gradually changes from large block breaking to small block breaking. The absorbed energy density is less affected by the strain rate when the strain rate is between 54 s−1 and 143 s−1, and the absorbed energy density rate correlation increases significantly when the strain rate is higher than 143 s−1. This study can provide a reference for the block damage of deep sandstone.

Study on the Degradation Law of Artificial Joint Surfaces with Natural Morphologies under Quasi-Static Cyclic Shearing

In this paper, a series of quasi-static cyclic shear tests were performed on artificial rock joint specimens with natural morphologies at different normal stress levels. After shearing, combined with 3D scanning technology and image processing, the 3D morphology parameter, A0θmax∗/(C+1), of 36 analyzed directions was measured to investigate the damage and degradation laws of the joint surfaces. The polar curves of the roughness parameter shrank from a circular to an elliptical shape, with the shear direction as the minor axis. The roughness degradation rates and the shear cycles were mutually interrelated with the normal stress levels, which had a tendency to be fast initially and then to slow down under higher normal stress. Influenced by the cyclic shear direction, the 3D roughness of the joint surfaces degenerated anisotropically and sustained the most serious damage along the shear direction. Two damage and degradation fitting formulas were proposed, which could aid the assessment of residual roughness under different stress histories and the cumulative wear degree.

Serial and Parallel Computation of Bone Scan Image Processing

Serial and Parallel Computation of Bone Scan Image Processing

Grey Correlation Analysis between Macro Mechanical Damage and Meso Volume Characteristics of SBS Modified Asphalt Mixture under Freeze-Thaw Cycles

The effect of freeze–thaw (F–T) in the seasonal frozen area would lead to damage to asphalt pavement. After water enters asphalt pavement, the water in voids would expand at a lower temperature, which could change the void content and number, affecting the macro mechanical properties of the asphalt mixture. The rapid development of CT scanning and digital image processing (DIP) provides powerful technical support for the research of asphalt mixture meso volume characteristics. In this paper, the mechanical properties of basalt fiber reinforced asphalt mixture subjected to F–T cycles were tested at different temperatures to clarify the decay law of mechanical properties under F–T cycles. Then, the meso images of the asphalt mixture under various F–T cycles could be obtained by using CT tomography. Based on DIP technology, the meso characteristic parameters of CT images for asphalt mixture were extracted, and the development of asphalt mixture freeze–thaw damage was further analyzed. The test results showed that with the F–T cycle, the macro mechanical properties of the asphalt mixture rapidly declined in the early stage of the F–T cycle and gradually tended to be flat. There would be serious damage inside the asphalt mixture in the late stage of the F–T cycle. The damage to the mechanical properties of the asphalt mixture under the F–T cycle can be attributed to the change in the internal mesostructure of the asphalt mixture. Based on the grey relational analysis theory, the formation of the connected void was the main factor affecting the damage in the early stage of the F–T cycle, while the formation of new voids mainly affected the later development of F-T damage.

Influence of fiber orientation on the mechanical responses of engineering cementitious composite (ECC) under various loading conditions

The mechanical performance of engineered cementitious composite (ECC) depends greatly on fiber orientation and distribution. In this paper, the effect of fiber orientation on ECC's mechanical properties was investigated using two different casting methods: a flow-induced casting was used to enhance the fiber orientation within ECC mixture and compared with the conventional casting. The fiber orientation was quantified using scanning electron microscope (SEM) and image processing. Mechanical tests on the specimens with various fiber orientations were performed. The failure processes of ECC specimens under compression and tensile tests were analyzed using digital image correlation (DIC) technique. The proposed flow-induced casting enhanced the fiber alignment in the flow direction. Consequently, ECC's mechanical properties were significantly improved with more finer cracks under uniaxial loading. In conclusion, the proposed flow-induced casting can be adopted as an effective approach to improve fiber bridging efficiency in ECC.

Effect of aggregate morphology characteristics on the voidage of aggregate loose packing based on 3D discrete element method

• The aggregate model with real morphology was generated by Clump method. • A 3D aggregate database considering real morphology was established. • The void spatial distribution of aggregate loose packing was studied. Reducing the voidage of aggregate loose packing can improve the workability of concrete, and aggregate morphology directly affects the voidage of aggregate loose packing. This paper combined 3D laser scanning and digital image processing (DIP) technology to perform statistical analysis on aggregate morphology characteristics such as sphericity, flatness, elongation and angularity index. A 3D aggregate database was built using the structured query language (SQL). On this basis, the discrete element model of loose packing was established by the gravity falling method (GFM), considering the natural morphology of aggregates; and the effect of aggregate morphology characteristics on the voidage and void spatial distribution of loose packing under different gradations was quantitatively studied. The results show that the voidage of aggregate loose packing decreases as aggregate sphericity increases and increases with the increase in angularity index. The effect of sphericity on the voidage of aggregate loose packing is about five times that of angularity index. In addition, the voidage in aggregate packing is arranged in Z-shape, and the larger the aggregate sphericity or, the smaller the angularity index, the more uniform the voids in the aggregate packing are distributed.

Effects of microstructure on compressive strength of silica sand-enhanced oil well cement at a wide temperature range.

The influence of microstructure of silica-enhanced cement on the mechanical performance of cement is difficult to describe. In this study, we used the scanning electron microscope and image processing method to investigate the relationship between the complicity of cement microstructure and compressive strength under various temperatures and curing times. Fractal dimension was applied to describe the complicity of silica-enhanced cement. The relationships among compressive strength, fractal dimension, temperature, curing time and pore structure of cement were identified. The results show that curing time directly controls the complicity of microstructure of silica-enhanced cement and compressive strength by altering the pore orientation and macropore ratio in silica-enhanced cement. The curing temperature affects the complicity of cement microstructure and compressive strength indirectly by changing the ratio of micropore and small pore. The fractal dimension of silica-enhanced cement shows good correlation with compressive strength. Pore size distribution is the most important factor that influences the complicity of cement matrix and compressive strength of silica-enhanced cement. When building up the macroscopic mechanical performance model of silica-enhanced cement, we should consider the influence of pore size distribution in cement under different curing temperatures and times on the complicity of cement microstructure.

Microstructural analysis and multiscale modeling for stiffening and strengthening of consolidated earthen-site soils

While experimental explorations to consolidate earthen-site soils using composite materials have obtained desirable reinforcing effect, few modeling efforts were conducted to reveal how microstructures of consolidated soils affect their effective stiffness and strength. The current study develops a multiscale modeling technique to quantify the stiffening and strengthening effects of consolidants to earthen-site soils. Specifically, a micromechanics-based finite element method is applied to simulate the homogenized constitutive relations of the untreated and consolidated soils, based on the microstructures from scanning electron microscopy images and image-processing procedures. Multiscale models are used to examine the influence of input properties of consolidants on the sensitivity of mechanical properties of the earthen-site samples. Comparison between modeling and experimental results shows a satisfactory agreement. The macroscopic mechanical properties of soils are remarkably affected by their microstructures. This study demonstrates the feasibility of integrating scanning electron microscopy and image processing technology into the finite-element modeling for stiffening and strengthening analysis of consolidated earthen-site soils.

Computed tomography scans image processing for nasal symptoms severity prediction

This paper aims to use a new technique of computed tomography (CT) scan image processing to correlate the image analysis with sinonasal symptoms. A retrospective cross-sectional study is conducted by analyzing the digital records of 50 patients who attended the ear, nose and throat (ENT) clinics at King Abdullah University Hospital, Jordan. The coronal plane CT scans are analyzed using our developed software. The purposes of this software are to calculate the surface area of the nasal passage at three different levels visible on coronal plane CT scans: i) the head of the inferior turbinate, ii) the head of the middle turbinate, and iii) the tail of the inferior turbinate. We employ image processing techniques to correlate the narrowing of nasal surface area with sinonasal symptoms. As a consequence, obstruction in the first level is correlated significantly with the symptoms of nasal obstruction while the narrowing in the second level is related to frontal headache. No other significant correlations are found with nasal symptoms at the third level. In our study, we find that image processing techniques can be very useful to predict the severity of common nasal symptoms and they can be used to suggest treatment and to follow up on the case progression.

Spatial-Temporal Speckle Variance in the En-Face View as a Contrast for Optical Coherence Tomography Angiography (OCTA).

Optical Coherence Tomography (OCT) is an adaptable depth-resolved imaging modality capable of creating a non-invasive ‘digital biopsy’ of the eye. One of the latest advances in OCT is optical coherence tomography angiography (OCTA), which uses the speckle variance or phase change in the signal to differentiate static tissue from blood flow. Unlike fluorescein angiography (FA), OCTA is contrast free and depth resolved. By combining high-density scan patterns and image processing algorithms, both morphometric and functional data can be extracted into a depth-resolved vascular map of the retina. The algorithm that we explored takes advantage of the temporal-spatial relationship of the speckle variance to improve the contrast of the vessels in the en-face OCT with a single frame. It also does not require the computationally inefficient decorrelation of multiple A-scans to detect vasculature, as used in conventional OCTA analysis. Furthermore, the spatial temporal OCTA (ST-OCTA) methodology tested offers the potential for post hoc analysis to improve the depth-resolved contrast of specific ocular structures, such as blood vessels, with the capability of using only a single frame for efficient screening of large sample volumes, and additional enhancement by processing with choice of frame averaging methods. Applications of this method in pre-clinical studies suggest that the OCTA algorithm and spatial temporal methodology reported here can be employed to investigate microvascularization and blood flow in the retina, and possibly other compartments of the eye.

Particle and Particle Agglomerate Size Monitoring by Scanning Probe Microscope

In the present study, the use of a scanning probe microscope is described for monitoring the sizes of nanoparticles. Monitoring is the process of acquiring and analysing the set of overlapping images. The main analysis steps are image segmentation, determination of nanoparticles allocation and their sizes, determination of the overlap of images with one another, and exclusion of repeating measurements for the formation of the correct particle-size sampling. The thorough examination of commercial scanning probe microscopes, software, and image processing libraries showed that their capabilities are limited for image segmentation and determination of sizes in complex structured images. A method based on the surface curvature computation is proposed for the image segmentation (allocation of particles) and determination of particle sizes. The curvature is estimated using the surface area approximation with respect to the circumference. It is proposed to use sample displacement sensors as an aid for image stitching.

Estimation of the k-Value for Head CT Using ICRP-103 Tissue Weighting Factors

Multi-slice x-ray CT scanners are in highly use by physicians to assist them in diagnosing patients disease due to advances in their scanning speed, image processing and image quality. However, this trend results in patients being exposed to many fold higher doses compared to those for general x-ray radiography. This makes CT machines the major source of unwanted dose to the population from medical x-ray procedures. The CTDIvol and DLP parameters are quantities of concern in radiation protection measures. This study was aimed to examine the effective dose received by patients underwent head CT procedures In this paper we present our estimation of the k-value calculated from the DLP from the CT machine in the participating hospital using the ICRP 103 weighted tissue factor. Dose parameters were acquired from the machine and calculations were carried out using the ImPACT CTDosimetry software. We also compared the received doses by age and gender groups. We found that the doses are dissimilar between age groups and between male and female patients.

Transparent characterization and quantitative analysis of broken gangue’s 3D fabric under the bearing compression

Broken gangue has been extensively used in rockfill dams, subgrade, embankment, foundation cushion and other engineering construction. The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness, stability and safety of these structures (buildings), and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation. In this study, the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test, image processing and 3D reconstruction technology, and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed. The results show that: In the loading stage of 0–2 MPa, the sharp corners, thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression; in the loading stage of 2–8 MPa, a large number of larger particles in the sample are crushed in the mode of fragmentation; in the loading stage of 8–10 MPa, the breakage degree of samples is relieved. The axial displacement of the block inside the sample occurs, as well as the lateral displacement of the block converging to the central axis of the sample. In the rapid deformation stage, the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block; in the slow deformation stage, it is mainly caused by the breakage of the block; in the stable deformation stage, it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.

Time-Resolved, Dynamic Computed Tomography Angiography for Characterization of Aortic Endoleaks and Treatment Guidance via 2D-3D Fusion-Imaging.

In the United States, more than 80% of all abdominal aortic aneurysms are treated by endovascular aortic aneurysm repair (EVAR). The endovascular approach warrants good early results, but adequate follow-up imaging after EVAR is imperative to maintain long-term positive outcomes. Potential graft-related complications are graft migration, infection, fraction, and endoleaks, with the last one being the most common. The most frequently used imaging after EVAR is computed tomography angiography (CTA) and duplex ultrasound. Dynamic, time-resolved computed tomography angiography (d-CTA) is a reasonably new technique to characterize the endoleaks. Multiple scans are done sequentially around the endograft during acquisition that grants good visualization of the contrast passage and graft-related complications. This high diagnostic accuracy of d-CTA can be implemented into therapy via image fusion and reduce additional radiation and contrast material exposure. This protocol describes the technical aspects of this modality: patient selection, preliminary image review, d-CTA scan acquisition, image processing, qualitative and quantitative endoleak characterization. The steps of integrating dynamic CTA into intra-operative fluoroscopy using 2D-3D fusion-imaging to facilitate targeted embolization are also demonstrated. In conclusion, time-resolved, dynamic CTA is an ideal modality for endoleak characterization with additional quantitative analysis. It can reduce radiation and iodinated contrast material exposure during endoleak treatment by guiding interventions.

Response of Floc Networks in Cemented Paste Backfill to a Pumping Agent

Cemented paste backfill is critical for the development of green mines, the safe exploitation of mineral resources deep underground, and the efficient disposal of solid wastes produced by mining. In this paper, the mechanism underpinning how the pumping agent works was studied. The number, area, and fractal dimension of pores in the microstructure of fresh paste were quantitatively analyzed using scanning electron microscopy (SEM), image processing, and fractal theory, and the response of flocs was investigated. The results show that floc networks disintegrated and the liquid network became the dominant structure under the action of the pumping agent, which enhanced the lubrication and promotion of multi-scale particles. In addition, the force chains became fragile and scattered, diminishing the yield stress of the paste. The pores had a more homogenized dimension and the porosity was 15.52% higher. The increase in the fractal dimension of the pores indicated that there was a higher self-similarity, in terms of microstructure, with a strengthened liquid network. The migration of floc structures contributed to the enhancement of the fluidity and rheology of the paste. This study provides insights into the effects of floc and liquid networks on the performance of paste, and it is of engineering significance in terms of realizing safe and efficient CPB operations.