Computed Tomography Scanning Technology Research Articles

Study on microscopic mechanisms of slurry infiltration in calcareous sand based on CT scanning

A novel detachable microslurry infiltration device tailored for computed tomography (CT) scanning was developed. Using this device, a series of slurry infiltration tests was conducted on calcareous and Fujian sand columns with various bentonite slurry concentrations. CT scanning technology nondestructively captured the cross-sectional image slices of each specimen for analysis. A comprehensive image processing methodology was deployed to precisely differentiate the three phases—calcareous sand, slurry, and air—enabling 3D reconstruction of the infiltrated sand column. This approach combines three techniques: threshold segmentation, the watershed algorithm, and deep learning. Distinctive particle morphologies inherent to the calcareous and Fujian sands were observed. Notably, CT scans revealed a markedly greater angularity and irregularity of the calcareous sand compared with the Fujian sand, leading to different pore characteristics. Given an identical permeability coefficient, the calcareous sand porosity exceeded that of the Fujian sands. Furthermore, image analyses revealed distinct features of filter cake formation in these two soil columns. In calcareous sands with finer grain sizes, the slurry particles were more prone to clogging because of constricted and irregular seepage pathways. Conversely, with increasing particle size, the internal pores of the calcareous sand particles augmented channels for slurry infiltration, hindering filter cake formation.

Mechanism of asphalt concrete reinforced with industrially recycled steel slag from the perspectives of adhesion and skeleton

This research investigated the reinforcement mechanism of steel slag recycling in asphalt concrete from the perspective of adhesion and skeleton. Bonding performance between steel slag and bitumen was assessed by the calculation of coating area and peeling area, as well as the area detection by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). Computed Tomography (CT) scanning was used to determine the bitumen absorption characteristics of steel slag. Mechanical characteristics of steel slag mixture during compaction period and service period were evaluated by continuous compression test with Universal Testing Machine (UTM-25). A combination of CT scanning and image processing technology were used to quantify skeleton contact characteristics. The results indicated that bonding performance of bitumen with steel slag was obviously better than basalt after long-term erosion. The surface pores of steel slag absorbed excessive bitumen as anchoring and embedding effect, accounting for 20.24% of the total steel slag bitumen absorption in maximum. Steel slag skeleton of SMA gradation was found easily to be compacted during construction period and more resistant to loading during service period. In addition, there were more contact points in steel slag asphalt concrete, resulting that steel slag asphalt concrete had better stability. The contact points were different in different particle size ranges, and it was suggested that steel slag with particle size of 9.5–16.0 mm and 2.36–4.75 mm should be preferred.

Image-Guided VATS in the Hybrid Operation Room Facilitates Early Diagnosis and Concurrent Treatment of Subcentimeter Nonpalpable Lung Nodules.

As lung cancer screening increases, the detection of small, nonpalpable lung lesions is on the rise. The hybrid operation room (OR), which combines percutaneous or endobronchial fiducial placement with on-table computed tomography (CT) and fluoroscopic guidance, improves localization and facilitates the diagnosis and treatment of smaller, nonpalpable lung nodules with greater accuracy. In 35 consecutive months, 55 veterans underwent 60 image-guided video-assisted thoracic surgery procedures for lesion resection. Of the cases, 36% were found during lung cancer screening. All patients received their care in the hybrid OR, where cone-beam CT scan technology was used to place an average of 1.6 fiducials percutaneously (n = 55) or via augmented navigational bronchoscopy (n = 5). A total of 66 lesions were resected. The median lesion size was 8 mm with an interquartile range of 6 to 14. The patients underwent nonanatomical resection with lymph node dissection using radiologic guidance. When indicated, an anatomical resection was subsequently performed. Of 47 total non-small cell lung cancer lesions, 83% were diagnosed at stage IA1 or IA2. The median surgical margin was 15 mm; the margin was usually 1.5 times as wide as the lesion. The hybrid OR technology gives a 3-dimensional assessment of the small lung lesions, allowing for a tissue-saving resection while achieving good surgical margins. During lung cancer screening, smaller, nonpalpable lung nodules are frequently found. This technology allows resection of subcentimeter lesions, which would otherwise be unresectable at this early stage, possibly improving survival.

Adaptive Gaussian Wiener Filter for CT-Scan Images with Gaussian Noise Variance

Medical imaging plays an important role in modern healthcare, with Computed Tomography (CT) being essential for high-resolution cross-sectional imaging. However, Gaussian noise often occurs within the CT scan images and makes it difficult for image interpretation and reduces the diagnostic accuracy, creating a significant obstacle to fully utilizing CT scanning technology. Existing denoising techniques have a hard time balance between noise reduction and preserving the important image details, failing to enable the optimal diagnostic precision. This study introduces Adaptive Gaussian Wiener Filter (AGWF), a novel filter aims to denoise CT scan images that have been corrupted with various Gaussian noise variance without compromising the image details. The AGWF combines the Gaussian filter for initial noise reduction, followed by the implementation of Wiener filter, which can adaptively estimate noise variance and signal power in localized regions. This approach not only outperforms other existing techniques but also showcases a remarkable balance between noise reduction and image detail preservation. The experiment evaluates 300 images from the dataset and each image is corrupted with Gaussian noise variance to ensure a comprehensive evaluation of the AGWF’s performance. The evaluation indicated that AGWF can improve the Signal-to-Noise Ratio (SNR) value and reduce the Root Mean Square Error (RMSE) and Mean Square Error (MSE) value, showing a qualitative improvement in CT scan imagery. The proposed method holds promising potential for advancing medical imaging technology with the implementation of deep learning.

A phase-field lattice model (PFLM) for fracture problem: Theory and application in composite materials

In the present work, a phase-field lattice model (PFLM) is proposed to model fracture problems. The element deletion process and oversimplified failure criterion of the classical lattice model not only lead to a strong mesh sensitivity but also limit the method’s application to various materials and fracture modes. Hence, a smeared form of crack is introduced into the lattice model to deal with these problems. The model exploits discontinuous discrete methods to model the propagation of three-dimensional cracks by characterizing the crack with a phase-field variable. Moreover, by regarding the crack propagation process as a multi-field problem composed of a displacement field and a phase-field, a flexible and robust algorithm is established, in which the crack path can be obtained directly by resolving the governing equations. Numerical simulations were performed and compared with the experimental results and other numerical models. It is shown that the PFLM can capture the main features of the fracture for both brittle and quasi-brittle materials. To further demonstrate the performance of the model, a mesoscale system of cement composite generated by computed tomography scanning technology was examined. The result demonstrates that the fracture of composite materials can also be well predicted.

Modeling knot features using branch scars from Mongolian oak (Quercus mongolica).

Wood quality is an important indicator for modern sawmills. Internal wood characteristics can be derived from their correlations with external appearances. In this study, we developed linear regression models to predict knot size from surface features of Mongolian oak (Quercus mongolica) using data collected from 53 trees. For this, manual measurements and X-ray computed tomography scanning technology was respectively used to obtain internal and external features of 1,297 knots. Our results showed that Mongolian oak knots were generally concentrated in the middle part of oak stems, with fewer knots observed at the top and base. The parameters of knot and scar showed significant correlations (P<0.01), where length and diameter of the corresponding external scar increase with increasing the length and diameter of a knot. The corresponding external scar can be used as an effective indicator to predict the internal value of oak logs. The accuracy of our constructed model is more than 95% when assessed against independent test samples. These models thus can be applied to improve the practical production of oak timber and reduce commercial loss caused by knots. These additional data can improve the estimation of the influence of knots on wood quality and provide a theoretical foundation for investigating the characteristics of hardwood knots.

Shale damage simulation considering shale swelling during shale-liquid interaction

Shale-liquid interactions can lead to shale swelling, shale damage and affect the mechanical and other properties of shale. The relationship between shale swelling and shale damage was not well understood. A better understanding of the relationship is essential for drilling and fracturing designs. In this work, we employ shale swelling tests, computed tomography scanning technology and numerical simulation to understand the relationship between shale swelling and shale damage. The experimental results show that the shale swelling is 0.23% after the experiment. When the shale swelling is small, the damage is weak. However, the shale damage growth rate is 495.05% when the shale swelling rate increases by 0.19%, and macrofractures are formed. Using COMSOL with MATLAB, we further explore the relationship between shale damage and shale swelling. The simulation results show that shale swelling has an important effect on shale damage, and this effect is verified by comparing the simulation and experimental results. Shale damage is weak or even absent when shale swelling is not considered, while the distinct shale damage can be observed when shale swelling is considered. The increase of shale swelling leads to the increase in shale damage, which leads to more obvious fractures expansion, resulting in an increase in permeability. When shale swelling is 0.4%, the permeability at the end of the simulation is 322% higher than the initial permeability. The variation in stress at 0.4% shale swelling is 21 times that without considering shale swelling, and the large variations in stress are an important factor in shale damage. The higher the in-situ stress, the lesser is the tendency for shale damage to occur. Shale damage occurs at high injection pressures, even when shale swelling is low. In addition, the more complex the fracture network, the higher is the tendency for shale damage to occur, and the permeability after the simulation was 6% higher than that of bedding model. Therefore, fracturing methods with high injection pressures should be used, and the hydraulic fracturing should be conducted at locations where natural fractures develop to achieve significant shale-liquid interactions and better hydraulic fracturing results.

Three-Dimensional Reconstruction of Monochamus alternatus Galleries Using CT Scans.

Simple SummaryAs one of the most important boring pests in China, the longhorn beetle Monochamus alternatus directly damages or kills pine trees as a vector of pine wood nematode disease. The study of the distribution of M. alternatus and its gallery construction behavior is key to exploring the survival and reproductive mechanisms and population variation, as well as the associated disaster prevention and control planning. In this study, CT technology was used to scan wood segments of Pinus densiflora harmed by M. alternatus, and three-dimensional reconstruction technology was used to obtain gallery models. The results showed that the gallery types of M. alternatus were single and most of them were C-shaped, and a few were S-shaped or Y-shaped. There was no significant difference in the structural parameters of the three galleries. Each gallery has only one larva, which does not collude with each other. CT scanning and three-dimensional reconstruction technology can realize the non-destructive identification and detection of the gallery of M. alternatus, which provides a new idea and method for understanding its hidden feeding behavior and control strategy.As a vector of pine wood nematode disease, Monochamus alternatus is wood-boring, cryptic, and extremely difficult to control—features that have made them a disastrous problem. In this study, we present a method of scanning the galleries of Monochamus alternatus using CT (computed tomography) technology to obtain their systematic structure via 3D (three-dimensional) reconstruction, so as to clarify the gallery types and their structural parameters. TLC (thin-layer chromatography) scanning on wood segments damaged by M. alternatus was performed using a 128-row spiral CT GE Revolution EVO to obtain 64-layer CT scanned images. From the scanned images, we were able to clearly identify the beetle larvae and their galleries. The galleries were clearly delineated from the peripheral xylem, except for parts that were blocked by a frass–feces mixture, which were slightly blurred. Three-dimensional reconstruction of the galleries showed that most of the gallery types were C-shaped, and a few were S-shaped or Y-shaped. There was only one larva per gallery, and the galleries were separate. The vicinity of the entrance hole and the anterior part of the pupal chamber were blocked with a frass–feces mixture. There were no significant differences among the galleries’ parameters, such as the width of the entrance holes, tunneling depth, vertical length, blockage length and volume, total length of the galleries, and boring volume. With MIMICS (Materialise’s interactive medical image control system) image processing software, the images of each layer were made into a composite image, providing an effective way to visualize the 3D distribution of galleries. Using the methodology outlined in this study, both a single gallery structure and the spatial distribution of multiple galleries of M. alternatus can be shown, and the specific parameters of galleries can also be accurately calculated, which provides new ideas and methods for carrying out ecological and scientific research and precise prevention and control techniques of M. alternatus.

Investigation on the evolution characteristics of bed porous structure during iron ore sintering

To better understand the evolution characteristics of bed porous structure during iron ore sintering, X-ray computed tomography scanning technology was used to analyze the pore parameters in different areas of the sintering bed. A pore skeleton structure model was established to study the characteristics of the airflow channels in different zones. The absolute permeability of different areas was calculated through simulation, and the corresponding streamline and pressure drop distribution were analyzed. The results show that the porosity of raw material zone, high-temperature zone, and sintered zone increases gradually, which are 37.69%, 46.41%, and 55.57%, respectively. The absolute permeability calculation results of the raw material zone and sintered zones are 792.49 μm2 and 20560.80 μm2, while the tortuosity is 1.77 and 1.45, respectively. Compared with the raw material zone, the flow streamline in the sintered zone is thicker and denser, the airflow resistance and the pressure drop are minor.

Construction of complex digital rock physics based on full convolution network

Digital rock physics (DRP) is a paramount technology to improve the economic benefits of oil and gas fields, devise more scientific oil and gas field development plans, and create digital oil and gas fields. Currently, a significant gap is present between DRP theory and practical applications. Conventional digital-core construction focuses only on simple cores, and the recognition and segmentation effect of fractures and pores of complex cores is poor. The identification of rock minerals is inaccurate, which leads to the difference between the digital and actual cores. To promote the application of DRP in developing oil and gas fields, based on the high-precision X-ray computed tomography scanning technology, the U-Net deep learning model of the full convolution neural network is used to segment the pores, fractures, and matrix from the complex rock core with natural fractures innovatively. Simultaneously, the distribution of rock minerals is divided, and the distribution of rock conditions is corrected by X-ray diffraction. A pore–fracture network model is established based on the equivalent radius, which lays the foundation for fluid seepage simulation. Finally, the accuracy of the established a digital core is verified by the porosity measured via nuclear magnetic resonance technology, which is of great significance to the development and application of DRP in oil and gas fields.

Damage constitutive model of gas-bearing coal using industrial CT scanning technology

Determining the deformation characteristics and mechanical behavior of gas-bearing coal is beneficial to understanding the phenomena and rules of dynamic disasters during coal mining. In this study, a computed tomography (CT) scanner and a triaxial loading seepage system were used to perform CT scanning tests on gas-bearing coal under triaxial compressive conditions. We processed the CT images in different deformation stages of the gas-bearing coal and analyzed them with a digital image processing technology to depict dynamic evolution damage trend. In addition, we employed a fracture area projection method to propose a new damage variable and theoretically constructed a new damage constitutive model. The results showed that the coal specimens became prone to increased instability and damage as gas pressure increased. The growth and expansion of fissures in gas-bearing coal were heterogeneous and anisotropic and mainly experienced three processes, that is, closure in the compaction stage and elasticity stage, expansion in the strain-hardening stage, and sharp propagation and interconnection in the post-peak stage. With the progression of fracture propagation, the degree of damage gradually decreased then increased. The proposed new damage variable was more suitable than the traditional damage variable for depicting the damage degree and damage evolution process. Furthermore, the proposed new damage constitutive model well mirrored the deformation behavior of gas-bearing coal under triaxial compressive loads.

Experimental study of durable low-friction concrete contacts for precast segmental columns with resettable sliding joints

Planar sliding joints have been introduced to precast segmental bridge columns to alleviate the detrimental effects of earthquakes. However, residual sliding movements may result from strong shaking. Resettable sliding joints comprising V-shaped or W-shaped interfaces of gentle inclinations have been proposed to achieve better resilience against seismic actions in regions of moderate to high seismicity. However, possible deterioration of the frictional performance at the concrete contact surfaces may affect the resetting performance of these joints. In this regard, the tribological features, performance and durability at the interface of resettable sliding joints in precast segmental bridge columns were investigated experimentally utilizing 3D printed moulds and computed tomography scanning technology. Various surface treatment and lubrication methods were evaluated monthly up to 360 days after casting based on a modified cyclic direct shear apparatus at high loading pressure. Results show that high-performance PTFE grease lubricant is useful in achieving and maintaining favourable coefficients of friction as low as 0.05.

Terahertz Nondestructive Testing Method of Oil-paper Insulation Debonding and Foreign Matter Defects

Defects, such as debonding and foreign matters in transformer insulation paperboard, lead to local field strength concentration, thereby seriously affecting the safe operation of equipment. At present, industrial X-ray computed tomography scanning technology is mostly used to detect such defects. However, the equipment is expensive, the operation is complicated, and radiation hazard exists. In this study, terahertz time domain spectroscopy is introduced to explore the nondestructive testing method of oil-paper insulation defects. Three typical insulation paperboard defects of interface debonding, metal foreign matter mixing, and local carbonization traces were taken as the research objects. An artificial defect model is prepared. The time and frequency domain waveform characteristics of terahertz pulse wave propagating in the defect model are tested and analyzed. The results show that when the thickness of insulation paperboard covering is less than 5 mm, based on the amplitude and delay characteristics of terahertz time-domain signal, the location and size of typical internal defects can be accurately obtained, and time spectrum imaging can be realized. This study proves theoretically and experimentally the feasibility of noncontact and nondestructive testing for the internal defects of insulation paperboard by using terahertz technology.

Use of Computed Tomography Scan Technology to Explore the Porosity of Concrete: Scientific Possibilities and Technological Limitations

This paper shows the scientific possibilities of computed tomography for the study of concrete porosity. The enormous technological advances in computed tomography equipment used in materials research, with increasingly higher energy, better resolution and smaller pixel size will allow, in the near future, viewing pore sizes that are currently unthinkable, competing in resolution with the traditional techniques of mercury porosimetry and nitrogen adsorption. The challenge at that time (and to a lesser extent today) will be how to extract as much information as possible from the large amount of data provided by computed tomography equipment. In this article, through the study of six cubic specimens of 40 mm sides, different techniques of extraction and presentation of the information are shown, which help us to better understand the characterization of the morphology and distribution of the pores inside the concrete matrix. This information is essential to understand some of the macroscopic responses of the concrete.

Influence of Fibers and Curing Conditions on the Pore Morphology in Plain and Fiber-Reinforced High-Performance Concrete through the Use of Computed Tomography Scan Technology

This paper analyzes the pore morphology of two different concrete mixtures (plain and fiber-reinforced) under two different curing conditions, through the use of a CT scanner and post-processing software. Twelve cylinders of 45.2 mm in diameter and 50 mm in height were cast. Half of the specimens were kept in a humidity-controlled room, at 20 °C and 60% humidity, and the rest in a curing room, at 20 °C and 100% humidity. All the specimens were scanned at the age of 28 days, using a micro CT scanner. The results reveal that the presence of fibers substantially modifies the pore morphology in the way of increasing the volume of voids and the pore-size, reducing the shape factor of the voids and reorienting the voids toward a direction more aligned to the one showed by the fibers. In general, the curing conditions do no exhibit a great impact on the results.

Characterizing effects of mechanical compaction on macropores of reclaimed soil using computed tomography scanning

To study the effects of mechanical compaction on soil macropore structure in the process of reclamation, this study investigated reclaimed soil mechanically compacted in coal mining area with high groundwater level. The computed tomography scanning technology was employed to get soil slice images, and ArcGIS® was used to analyze the porosity, number, size, morphology, and distribution of macropores in reclaimed soil, at different compaction times (0, 1, 3, 5, 7, and 9) and depths (0–20, 20–40, and 40–60 cm). Our results proved that the mechanical compaction could decrease the macroporosity, number, and equivalent diameter (ED) of the macropores in reclaimed soil, while the morphology became rounded. The distribution of macropore ED was steeper and more asymmetrical than macropore circularity. However, mechanical compaction could make them flat and symmetrical. The macroporosity, number, ED, and circularity of macropores in packing layer (40–60 cm) were smaller than backfilling top layer (0–20 cm) and sublayer (20–40 cm). Thus, we suggest that subsoiling in packing layer is responsible for the improved macropore characteristics. Moreover, these macropores will possess better permeability if the compaction times are controlled.

Computed tomography (CT) scanning of internal log attributes prior to sawing increases lumber value in white spruce (Picea glauca) and jack pine (Pinus banksiana)

The increased pressure on timber supply due to a reduced forest land base urges the development of new approaches to fully capture the value of forest products. This paper investigates the effects of knowing the position of knots on lumber volume, value, and grade recoveries in curve sawing of 31 white spruce (Picea glauca (Moench) Voss) and 22 jack pine (Pinus banksiana Lamb.) trees. Internal knot position was evidenced by X-ray computed tomography (CT) imaging, followed by the application of a knot-detection algorithm allowing log reconstruction for use as input in the Optitek sawing simulation software. Comparisons of the three levels of sawing optimization (sweep up, shape optimized, and knot optimized) revealed that considering internal knots before log sawing (e.g., knot optimized) generated 23% more lumber value for jack pine and 15% more for white spruce compared with the traditional sweep-up sawing strategy. In terms of lumber quality, the knot-optimized strategy produced 38% more pieces of grade No. 2 and better in jack pine and 15% more such pieces in white spruce compared with the sweep-up strategy. These results indicate a great potential to increase manufacturing efficiency and profitability by implementing the CT scanning technology, which should aid in developing a strong bioeconomy based on an optimized use of wood.

Applications of computed tomography (CT) scanning technology in forest research: a timely update and review

Organic materials of woody plants are complex and show internal, structural, and morphological variations due to genetic and environmental influences. Variability can be observed in stems, branches, leaves, and roots. Nondestructive and noninvasive technologies have been proposed to assess this variability. Computed tomography (CT) scanning, originally designed for medical diagnostics, permits the measurement of wood properties in situ (e.g., wood density, moisture content, internal defects, annual growth) and crown traits that characterize branching pattern geometry and canopy space occupancy for small-sized trees. Since Wei et al.’s (2011, Can. J. For. Res. 41(11): 2120–2140, doi: 10.1139/x11-111 ) review on the assessment of wood quality for optimized manufacturing processes using a CT scanner, several important developments have occurred, motivating the preparation of an update. We provide technical clarifications about the scales of observation and resolution; report on recent studies in which CT scanning was applied with research objectives beyond wood quality assessment for an optimized manufacturing of forest products; and stress the importance of analytical procedures for the graphical and quantitative analyses of CT scanning data (images and numbers) and the need for specialized algorithms and software. With this review, readers are expected to be well informed of the avenues offered by CT scanning technology in forest research in general.

Experimental and Numerical Study on CO2 Sweep Volume during CO2 Huff-n-Puff Enhanced Oil Recovery Process in Shale Oil Reservoirs

CO2 huff-n-puff has been proven to be the most effective enhanced oil recovery (EOR) method in shale oil reservoirs. The injected CO2 will replenish reservoir energy and penetrate the reservoir matrix to extract oil. However, the CO2 sweep volume during the huff-n-puff process has not been accurately evaluated by existing studies. In this paper, the CO2 sweep volume was investigated through experimental and numerical simulation methods. In the experimental study, the CO2 sweep areas were depicted by X-ray computed tomography scan technology. The results indicated that the ratio of the CO2 sweep area was 78.63% in the seventh huff-n-puff cycle, leading to a total oil recovery of 56.80%. The numerical simulation considered the mechanisms of molecular diffusion and nanopore confinement. The results showed that in the first huff-n-puff cycle, the gas sweep volume percentage was 9.47% after 100 days of huff period. In the gas swept volume, oil viscosity was reduced by 25.9% to 68.2%. After three cycles of CO2 ...

Characterization of the effects of detector angular misalignments and accuracy enhancement of X-ray CT dimensional measurements

Characterization of the effects of detector angular misalignments and accuracy enhancement of X-ray CT dimensional measurements