Three-dimensional Digital Reconstruction Research Articles

Digital and anatomical study of posterior atlantooccipital joint-occipital condyle-clivus screw technique

Objective: To investigate the screw placement parameters, feasibility and safety of posterior atlantooccipital joint-occipital condyle-clivus screw technique in Chinese people. Methods: Upper cervical spine CT images of 46 patients, including 24 males and 22 females, were collected with random number table from June 2019 to May 2020 in Ningbo No.6 Hospital. The patients aged 20-55 years, with a mean age of (39±9) years. Total of 92 sides of upper cervical spine models were obtained by Mimics 19.0 digital three-dimensional reconstruction, and screw placement was conducted simulately. The midpoint of transition zone between the posterior arch of atlas and the inferior articular process of lateral mass was selected as the screw entry point. The diameter and length of screws was 3.5 mm and 50 mm, respectively. Detailed morphometric measurements of the 92 atlantooccipital joint-occipital condyle-clivus screws were conducted. The distance between the screw and its surrounding important structures, screw inside and upper tilting angles, the length of screw trajectory in atlas and the length of screw trajectory on occipital side (occipital condyle-clivus) were all measured. Paired t test was performed on the parameters of left and right screw placement to confirm whether there was difference between the two sides. Results: In the 46 cases of upper cervical spine digital three-dimensional models, 92 posterior atlantooccipital joint-occipital condyle-clivus screws were implanted. All the screws were completely fixed in the clivus, without breaking through the upper sphenoid sinus, entering into the canalis spinalis and foramen magnum, and damaging the surrounding structures such as hypoglossal canal. The screw trajectory parameters between the left and right sides were slightly different, but there was no statistical differences between the two sides (P>0.05). The vertical distance between the screw entry point and the upper edge of atlas was (12.6±1.0) mm, the vertical distance between the screw entry point and the lower edge of atlas was (6.5±0.6) mm, the distance between the screw and the medial border of atlas vertebral artery foramen was (6.7±0.6) mm, the distance between the screw entry point and the medial wall of atlas was (6.6±0.7) mm, the distance between the screw outer margin and the hypoglossal canal was (5.5±0.6) mm, screw inside tilting angle was 21.2°±2.5°, screw upper tilting angle was 52.0°±3.4°, the length of screw trajectory in atlas was (12.1±0.9) mm, the length of screw trajectory on occipital side (occipital condyle-clivus) was (37.9±0.9) mm. Conclusion: The posterior atlantooccipital joint-occipital condyle-clivus screw technique can serve as a feasible and safe treatment for instability of the occipitocervical junction, which can be used as a new posterior occipitocervical fusion technique.

3D PLANNING IN ORTHOPAEDICS: AN ESSENTIAL TOOL FOR COMPLEX SURGERY

Abstract INTRODUCTION In orthopedic surgery, the appearance of three-dimensional digital reconstructions represented a clear before and after in the planning of highly complex surgeries. However, these reconstructions only allow to improve the visualization of the lesion. In recent years, new techniques have been incorporated, such as 3D printing of bone reconstructions, improving the understanding of the anatomy of each patient, allowing the simulation of possible treatments, and even their intraoperative manipulation. MATERIAL AND METHODS A 3D impression was made in surgical resin of a reconstruction of a CT of the cervico-thoracic spine, with a metastatic lesion in T2, in order to study the possible viability of an en-bloc vertebrectomy and the simulation of pedicle paths. RESULTS The feasibility of vertebrectomy was verified thanks to a better estimation of the available window size. Simulations were performed in the cervical pedicle paths, obtaining the best possible orientation according to the anatomy. Manipulation of the model in the surgical field allowed an in situ comparison with the exposed area, and optimized the result. CONCLUSIONS Planning and 3D printing in Orthopaedics is an indispensable tool when performing complex surgery. It allows to improve the understanding of the particular anatomy of each patient and simulate different treatments to obtain the best possible result.

A New Parameter, the Smallest Oblique Sagittal Area of the Neural Foramen, as an Index to Diagnose Cervical Neural Foramen Stenosis.

The objective was to reconstruct the cervical neural foramen and accurately measure the minimum oblique sagittal area of the neural foramen. Then, a quantitative diagnostic standard for cervical neural foramen stenosis was proposed and its value as an indication for surgery was evaluated. (1) CT data were used to reconstruct the neural foramen using Mimics software, and the minimum area was measured. (2) The optimal cut-off value was determined using a receiver operating characteristic (ROC) curve. (3) Patients who underwent single-segment surgery were divided into 2 groups according to the cut-off value. Then the postoperative neurological function improvement rate was analyzed to identify any significant difference between the 2 groups. A total of 1056 neural foramens were measured in 132 patients, of which 495 (46.88%) were diagnosed as radiculopathy by clinical neurological examination. The optimal cut-off value determined by the ROC curve was 25.95 mm2 (sensitivity 74.1%, specificity 80.9%) and the area under the curve (AUC) was 0.827 (95%CI: 0.803-0.849). There was a significant difference in the neurological function improvement rate between the 2 groups after surgery (P < 0.05). The intraclass correlation coefficient (ICC) was 0.969. Three-dimensional digital simulation reconstruction of CT data is a good measurement method. The optimal cut-off value determined here not only has a certain reference value for the diagnosis of cervical neural foramen bony stenosis, but also helps to select patients suitable for neural foramen decompression and can be used as a reference for surgical indication.

Application of superficial inferior epigastric artery flaps to repair oral and maxillofacial defects with the aid of digital three-dimensional reconstruction technique

Objective: To explore the application value of digital three-dimensional(3D) reconstruction technology in the repair of oral and maxillofacial defects with superficial inferior epigastric artery (SIEA) flap. Methods: Twelve cases of oral cancer patients, including 8 males and 4 females; aged (57.4±12.6) years, were selected from the Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Bengbu Medical College from January 2018 to October 2019 and were proposed to repair with SIEA flap. There were 10 cases of squamous cell carcinoma, one case of adenoid cystic carcinoma and 1 case of mucinous epidermal carcinoma. The data were imported into AW4.7 software for post-processing. The left or right dominant donor area was selected to clarify the origin, diameter, alignment, and location of penetration point of the flap blood supply, and digital 3D reconstruction technology was used to guide the flap preoperative design. Results: Eleven cases were repaired by SIEA flap in 12 patients, one case was repaired by superficial iliac artery flap because the source artery was undiscovered, one case had venous vascular crisis after surgery, and the rest of the flap survived. In 11 patients repaired with SIEA flap, there was no significant difference between the preoperative SIEA diameter measured by CTA [(1.0±0.3) mm] and the actual measured value [(1.1±0.3) mm] (P>0.05). The follow-up was 6 to 12 months, with an average of 10 months, and the donor-receiver areas were all healed in phase Ⅰ. No obvious complications occurred, and the abdominal scar was hidden. Conclusions: In the SIEA flap repair oral and maxillofacial defect reconstruction surgery, the use of digital 3D reconstruction technology can objectively reflect the diameter and the location of the superficial artery of the abdominal wall before surgery, effectively reduce the difficulty and risk of flap surgery.

Three-dimensional measurement analysis of midface morphology in Treacher Collins syndromes

To three-dimensionally calculate the craniofacial parameters of midface of patients with Treacher Collins syndrome (TCS) in China, in order to understand the changes in the spatial position relationship between the various anatomical structures of the midface. CT imaging data of TCS patients and age- and gender-matched normal populations between January 2013 and July 2020 was retrospectively analyzed. A total of 33 cases met the selection criteria for inclusion in the study, including 14 cases in the TCS group and 19 cases in the control group. ProPlan CMF 3.0 software was used to perform three-dimensional digital reconstruction of the craniofacial bone, measure the anatomical parameters of the midface, and analyze its morphological structure; at the same time perform three-dimensional digital reconstruction of the upper airway for morphological analysis (measure upper airway volume). CT images analysis revealed that all 14 patients with TCS presented the typical features with downward slanting of the palpebral fissures and different degrees of zygomatico-orbital complex dysplasia. Cephalometric and morphological analysis of the midface revealed that, multiple transverse diameters of the midface of TCS patients were significantly decreased when compared with the control group ( P<0.05), such as the width of the maxillary base, the length of the maxillary complex, and some distances related to the nasal morphology; but the distance between bilateral orbitales increased in TCS group ( P<0.05). Several anteroposterior distances in TCS group were decreased significantly when compared to control group and the distance between the skull base point and the posterior nasal spine was the most shortened ( P<0.05). But there was no significant difference of the distance between nasion and anterior nasal spine, which represented anterior midface height, between groups ( P>0.05). The skull base angle and SNB angle (the angle between the sella point-nose root point-inferior alveolar seat point) of the TCS group both decreased when compared with the control group ( P<0.05), but there was no significant difference in SNA angle (the angle between the sella point-nose root point-upper alveolar seat point) between the two groups ( P>0.05). The total volume of the upper airway was (24 621.07±8 476.63) mm 3 in the TCS group, which was significantly lower than that of the control group [(32 864.21±13 148.74) mm 3] ( t=2.185, P=0.037). The transverse distances, anteroposterior distances, and multiple craniofacial angles measurement of TCS patients were significantly decreased when compared to the control group, presented with different degrees of zygomatico-orbital complex dysplasia, nasal and maxillary dysplasia, but there was no obvious restriction in face height development. Reduced internal diameters of the upper airway maybe responsible for the decreased upper airway volume of patients with TCS.

Intensidad constructiva y visual en la obra inicial de Fargas y Tous (1954-1963)

&lt;p&gt;Las obras que Josep María Fargas y Enric Tous realizaron entre 1954 y 1963 constituyeron una particular manera de concebir la arquitectura moderna en España. Los limitados medios constructivos disponibles en el mercado de aquel entonces fomentaron en los arquitectos una intensa búsqueda de nuevas soluciones constructivas, evaluando rigurosamente en ellas no solo sus cuestiones técnicas, sino que también la manera en que estas se manifestaban visualmente. Esta predominante condición visual de las primeras obras de Fargas y Tous ha podido ser analizada por medio de un proceso de reconstrucción digital tridimensional de cuatro de las obras más representativas de este período. La intelección visual propiciada por el método ha sido plasmada en una secuencia de imágenes y texto. Con esto se espera poner en valor a un grupo de obras que, si bien ya no existen físicamente, se mantienen aún vigentes en muchos de sus principios arquitectónicos.&lt;/p&gt;

Computational capacity of pyramidal neurons in the cerebral cortex

The electric activities of cortical pyramidal neurons are supported by structurally stable, morphologically complex axo-dendritic trees. Anatomical differences between axons and dendrites in regard to their length or caliber reflect the underlying functional specializations, for input or output of neural information, respectively. For a proper assessment of the computational capacity of pyramidal neurons, we have analyzed an extensive dataset of three-dimensional digital reconstructions from the NeuroMorpho.Org database, and quantified basic dendritic or axonal morphometric measures in different regions and layers of the mouse, rat or human cerebral cortex. Physical estimates of the total number and type of ions involved in neuronal electric spiking based on the obtained morphometric data, combined with energetics of neurotransmitter release and signaling fueled by glucose consumed by the active brain, support highly efficient cerebral computation performed at the thermodynamically allowed Landauer limit for implementation of irreversible logical operations. Individual proton tunneling events in voltage-sensing S4 protein α-helices of Na+, K+ or Ca2+ ion channels are ideally suited to serve as single Landauer elementary logical operations that are then amplified by selective ionic currents traversing the open channel pores. This miniaturization of computational gating allows the execution of over 1.2 zetta logical operations per second in the human cerebral cortex without combusting the brain by the released heat.

High-quality Digital 3D Reconstruction of Microscopic Findings in Forensic Pathology: The Terminal Pathway of a Heart Stab Wound.

High-quality digital three-dimensional (3D) reconstructions of microscopic findings have been used in anatomical and histopathologic research, but their use in forensic pathology may also be of interest. This paper presents an application of these methods to better characterize the pathway of a stab wound of the anterior surface of the heart in a case of suicide. A portion of the heart wall including the stab wound was serially sectioned for microscopic analysis along the full extent of the wound. Histologic sections were digitally acquired, and a 3D reconstruction was created with ImageJ software for 3D computer graphics. This showed a full-thickness wound path extending to the endocardial surface of the left ventricle, curvilinear in appearance. After correction for shrinkage, 3D reconstruction allowed estimation of the dimensions of the myocardial injury and comparison of the appearance of the wound with the suspected knife used. The curvilinear appearance was considered to reflect injury during myocardial contraction. Complete microscopic sectioning and 3D reconstruction may allow virtual sectioning through various orientations and also provide useful forensic information for selected injuries.

Research on High Voltage Power Line extraction based on Transmission Line Point Cloud characteristics and Model fitting

High-voltage power line digitization is one of the key contents of intelligent inspection of transmission line. Airborne LiDAR has obvious advantages in three-dimensional digital reconstruction of high-voltage power line. In this paper, a power line extraction algorithm for transmission line corridor based on LiDAR point cloud data is proposed. According to the distribution characteristics of point clouds in transmission line corridors, rough extraction of power lines is carried out. Noise points are eliminated by improved Hough and RANSAC parabola fitting method. Then the power lines are segmented horizontally and vertically. According to the vertical parabola model of a single power line and the straight line model of water surface, the complete power lines are extracted by model growth algorithm. Line point. The experimental results show that the accuracy of the proposed algorithm is 99.6%.

Effective approaches to three-dimensional digital reconstruction of fragmented human skeletal remains using laser surface scanning

The preservation and reconstruction of anthropological and archaeological remains has been given considerable attention in recent years, particularly within the fields of forensic science and palaeoanthropology. However, few studies have tapped the potential of using 3D technology to reconstruct, remodel and recontour remains and artefacts for the purpose of human identification. The aim of this study was to use 3D technology for the reconstruction and remodelling of fragmented and missing elements of skeletal remains. This project presents the application of three dimensional (3D) modalities to two different simulated forensic case scenarios where an attempt was made to remodel the missing element of the human cranium and reconstruction of fragmented replicated human mandible was performed. The accuracy of the reconstructed model was affirmed based on the anatomical features and digital analysis and methods for use in forensic practice are recommended.

Three-Dimensional Digital Reconstruction of Ti2AlC Ceramic Foams Produced by the Gelcast Method.

A digital reconstruction technique is presented that generates three-dimensional (3D) digital representations of ceramic foams created by the foam-gelcasting technique. The reconstruction process uses information that is directly extracted from Scanning Electron Microscopy (SEM) images and offers a 3D representation of the physical sample accounting for the typically large pore cavities and interconnecting windows that are formed during the preparation process. Contrary to typical tessellation-based foam treatments, a spherical representation of the pores and the pore windows of the foams is assumed and a novel hybrid algorithm that combines a variation of Lubachevsky-type and Random Close Packing of Hard Spheres (RCPHS) algorithms has been developed to obtain near-optimum solutions to the packing problem of the spheres that represent the pores. Numerical simulations are performed directly on the 3D reconstructed foams to determine their gas permeability. The model predictions are compared with experimental gas permeability data that were obtained for the physical samples. The pore wall thickness can be treated as the single fitting parameter in the entire reconstruction process, although it is shown that images of sufficient resolution could eliminate the need even for that. The foams that are produced by this method yield quantitatively similar pressure drops with experiments for various superficial velocity values, with a very small deviation in the range of 1.7–2.8%. The proposed methodology could be utilized for the prediction of the permeability and transport properties of complex foamy porous structures, similar to the gelcast-type of foams, from a single SEM image of the foam sample without resorting to serial tomography or other structural information, thus saving considerable time and effort from experimental work.

Applied anatomy and three-dimensional visualization of the tendon-bone junctions of the knee joint posterolateral complex

BackgroundTo conduct an anatomical study of the fibular collateral ligament (FCL), popliteus tendon (PT), biceps femoris tendon (BT) and popliteofibular ligament (PFL) of the knee joint posterolateral complex (PLC) at the femoral and fibular tendon-bone junctions based on the Chinese Visible Human (CVH) and American Visual Human Project (VHP) datasets and to determine their morphology, contact area, center points and mutual distances with the aim of providing assistance for surgical tunneling scheme. MethodsTen knee joint datasets were selected for segmentation and three-dimensional digital reconstruction. Histological sections images were used to establish criteria for the segmentation. The PLC tendon-junctions were observed and studied. ResultsThe FCL and PT had constant attachment to the femur, and the FCL, BT and PFL had constant attachment to the fibula. The tendon-bone junctions of each PLC structure did not have a uniform morphology or the same contact area, but the location of the central point of the tendon-bone junction was similar and regularly attached. All measurements were smaller in the CVH dataset than VHP dataset. At the femoral tendon-bone junction, the average distance between the center points of the FCL and PT was 8.84 ± 1.62 mm (7.73 ± 1.44 mm in the CVH datasets and 9.50 ± 1.38 mm in the VHP datasets). ConclusionsThe authors propose a surgical tunneling scheme for femoral single-tunnel reconstruction in Chinese PLC reconstruction patients. The research data provide a theoretical basis and guidance for clinicians who need to design and select PLC surgical tunneling schemes.

A new specimen of Ziphiidae (Cetacea, Odontoceti) from the late Miocene of Denmark with morphological evidence for suction feeding behaviour.

A new fossil of Ziphiidae from the upper Miocene Gram Formation (ca 9.9–7.2 Ma) is described herein. Computed tomographic scanning of the specimen was performed to visualize the mandibles and to obtain a three-dimensional digital reconstruction. It possesses several characters of the derived ziphiids, such as the dorsoventral thickening of the anterior process of the periotic, the dorsoventral compression of the pars cochlearis and the short unfused symphysis. The specimen cannot be identified beyond the family level, because of the unusual nature of the preserved parts consisting of the mandibles, earbones and postcranial remains. It differs from other ziphiid species from the Gram Formation, Dagonodum mojnum, in its larger size and the more derived morphology of its mandibles and earbones. Its long and thickened stylohyal, combined with its reduced teeth, suggests that this new specimen relied primarily on suction feeding. By contrast, the other ziphiid species from the Gram Formation, D. mojnum, shows adaptations for a more raptorial feeding strategy. Assuming the two species were coeval, their co-occurrence at the same locality with two different feeding strategies, may represent a case of niche separation. They may have hunted different types of prey, thus avoiding direct competition for the same food resource.

Construction of digital three-dimensional reconstruction model of rabbit vascular network.

In order to study the construction of digital three-dimensional model of rabbit vascular network and provide a powerful basis for the model construction and image processing of human vascular network, in this study, rabbit abdominal and pelvic vessels are perfused with latex-bismuth oxide contrast agent. After that, the internal fibrous structure of the abdominal and pelvic vascular network in rabbits is studied by micro-computed tomography (Micro-CT). Angiography and post-processing software are performed. Firstly, six female rabbits are selected as the study subjects and are anesthetized by intraperitoneal injection of 12% chloral hydrate. After complete anesthesia, laparotomy is performed on the rabbits. The abdominal wall of the rabbit is cut longitudinally to expose the pelvic and abdominal cavity completely. The posterior peritoneum is found and opened. The catheter is inserted into the abdominal aorta and renal artery to complete the abdominal aorta and arterial intubation. Latex, bismuth oxide and potassium hydroxide are mixed in a ratio of 1:1:1 to form latex-bismuth oxide mixed solution as a mixed contrast agent for blood vessel perfusion. After the rabbit is perfused with mixed contrast medium, four organs, including bladder, uterus, small intestine and kidney, are selected as the research organs to construct the three-dimensional model of vascular network in this study. Finally, the above organs are scanned in vitro by micro-CT technology, and the original images of each organ are processed. Then, Mimics 17.0 software is used to build a digital three-dimensional model of the abdominal and pelvic vascular network in rabbits, obtain the information parameters of each network, and analyze the classification and diameter of blood vessels. The results show that the classification of bladder vascular network can only be divided into two levels, uterine vascular network can be divided into three levels, and small intestine and kidney vascular network can be divided into four levels. Therefore, the combination of micro-CT scanning and contrast agent can successfully construct a digital three-dimensional model of rabbit vascular network, which provides a new idea and method for the study of human abdominal and pelvic organs and physiological characteristics.

Application of three-dimensional digital reconstruction and printing technology in the clinical teaching of complex orthopedics

Objective To explore the effect of 3d digital reconstruction and printing technology on the teaching of complex orthopedics. Methods A total of 90 interns in the Second Affiliated Hospital of Inner Mongolia Medical University from September 2016 to September 2017 were selected as research subjects. According to the different teaching methods, they were divided into control group (n=45) and experimental group (n=45). The former received traditional teaching; the latter used three-dimensional digital reconstruction and printing technology to print out complex fracture models of patients, digitally reproduced fracture classification, developed scientific surgical plans through fracture models, and simulated surgical fixation methods. Examination was divided into clinical skills and written exam according to exam outline requirements; Self-cognitive ability score included professional interest, fracture understanding, etc. The satisfaction of the medical students in the experimental group was determined using self-made questionnaires. t test was used to compare data between groups. Results Experimental groups' scores for surgical skills (84.36±0.28) and theoretical knowledge (87.55±0.44) were higher than the control group, and the differences were statistically significant (P<0.05). The professional interest of the experimantal group was higher than that of the control group, and the difference was statistically significant (P<0.05). The students' classroom atmosphere was significantly better compared with the control group, and the difference was statistically significant (P<0.05). Conclusion Using 3 d digital reconstruction and printing technology to establish modes in complex orthopedics teaching process can effectively improve interns' surgical skills and theoretical knowledge, and promote student satisfaction. Key words: Complex trauma; Orthopedic teaching; 3d digital; 3d printing technology

Effectiveness of Parameters in Quantifying Root Canal Morphology Change after Instrumentation with the Aid of a Microcomputed Tomography.

The objective of this study was to analyse the effectiveness of some parameters which characterise the change in morphology in human root canals subjected to ProTaper rotary enlargement with the help of an X-ray microfocus computed tomography (MCT) and to introduce a novel parameter that is effective in quantifying changes in root canal morphology. Ten each straight and curved root canals with mature apices chosen from extracted human upper incisor and canine teeth were scanned with MCT before and after canal shaping using ProTaper rotary instruments in order to facilitate three-dimensional digital reconstruction and quantitative gauging of relevant instrumental parameters and changes therein (surface area and volume). Root canal geometry change and the effectiveness of shaping were quantified with Structure Model Index change (ΔSMI) and surface area change to volume change ratio (ΔSA/ΔV). These two parameters were also tested on simulated canals. Postinstrumentation cross-sectional changes were also analysed, but only on the plastic blocks. Statistical analysis of parameters was carried out to verify the significance of results. Analysis of cross-sectional shape of postinstrumented resin simulated canals showed statistically significant decrease in Form Factor (p<0.05) and statistically significant increase in Eccentricity (p<0.005). ΔSMI did not show significant difference between straight and curved canals. SMI values showed bidirectional change during root enlargement which questions the reliability of this metric in analysing instrumentation. Statistically significant (p<0.005) deviations in ΔSA/ΔV were quantified as 1.92 and 3.22 for straight and curved human canals, respectively. Instrumentation-induced canal geometry change was determined to be more pronounced in curved canals using the novel parameter ΔSA/ΔV. This has been proven as being a statistically accurate and reproducible parameter for quantitative characterisation of root canal geometry change and differentiation of preparational efficacy for both straight and curved root canals.

Application of three-dimensional reconstruction and printing as an elective course for undergraduate medical students: an exploratory trial.

Medical three-dimensional (3D) digital reconstruction and printing have become common tools in medicine, but few undergraduate medical students understand its whole process and teaching and clinical application. Therefore, we designed an elective course of 3D reconstruction and printing for students and studied its significance and practicability. Thirty undergraduate medical students in their second-year of study volunteered to participate in the course. The course started with three lessons on the theory of 3D digital reconstruction and printing in medicine. The students were then randomly divided into ten groups. Each group randomly selected its own original data set, which could contain a series of 2D images including sectional anatomical images, histological images, CT and MRI. Amira software was used to segment the structures of interest, to 3D reconstruct them and to smooth and simplify the models. These models were 3D printed and post-processed. Finally, the 3D digital and printed models were scored, and the students produced brief reports of their work and knowledge acquisition and filled out an anonymous questionnaire about their study perceptions. All the students finished this course. The average score of the 30 students was 83.1 ± 2.7. This course stimulated the students' learning interest and satisfied them. It was helpful for undergraduate students to understand anatomical structures and their spatial relationship more deeply. Students understood the whole process of 3D reconstruction and printing and its teaching and clinical applications through this course. It is significant and necessary to develop this course for undergraduate medical students.

Size Effects of Finite Element Model for Three-Dimensional Microstructural Modeling of Asphalt Mixture

Asphalt mixture is a particulate composite material consisting of aggregate, mastic, and air voids. The computed tomography (CT) image-based finite element approach is used as an effective method to simulate micromechanical response of asphalt mixture. For finite element analysis, the accuracy of the finite results is determined by the size of the finite element. In this paper, a voxel-based three-dimensional (3D) digital reconstruction model of asphalt mixture with the CT images after being processed was proposed. In this 3D model, the aggregate phase was considered as elastic materials while the asphalt mastic phase was considered as linear viscoelastic material. Four micromechanical digital models were generated, whose voxel sizes were 0.5 mm, 0.67 mm, 1.0 mm, and 2.0 mm, respectively. The four digital models were used to conduct uniaxial creep test for predicting creep stiffness modulus to investigate the effect of voxel size. Simulation results showed that the voxel sizes had a significant effect on creep stiffness modulus. For the creep simulation test, the most appropriate voxel size whose creep stiffness modulus changes within 2.5% is 1.0 mm with regard to time steps, computational time, aggregate, and mastic shape representations.

Study of Three-Dimensional Digital Core Reconstruction Based on Multiple-Point Geostatistics in a Cylindrical Coordinate System

Image inpainting and the extraction of different components from the electrical image log images are performed. After generating the training image, determining the appropriate template, multigrid, and event, calculating the conditional probability distribution function and defining the search tree, a three-dimensional digital core is reconstructed. A method for reconstructing three-dimensional digital cores based on multiple-point geostatistics in a cylindrical coordinate system is proposed in this paper. The electrical image log image is generated in a cylindrical coordinate system. The training image and conditional probability distribution function based on the cylindrical coordinate system are different from those based on a rectangular coordinate system. A three-dimensional digital core is evaluated based on an analysis of the local porosity and pore size. The experimental results show that three-dimensional digital core reconstruction based on multiple-point geostatistics in a cylindrical coordinate system is similar to the real core by statistical characteristics and connectivities. A three-dimensional digital core with high reliability can be used as a basis for numerical simulations in rock physics research.

文物数字化三维重建技术研究

文物数字化三维重建技术研究