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three-dimensional microstructure and Structural Representative Volume Element of the Intact and Remolded Loess

APPLIED SCIENCES-BASEL 2025年第6期15卷 3120-3120页

作者： Ma, Lina Zhang, Linxin Hou, Xiaokun Guo, Songfeng Qi, Shengwen Chinese Acad Sci Inst Geol & Geophys State Key Lab Lithospher & Environm Coevolut Beijing 100029 Peoples R China Univ Chinese Acad Sci Beijing 101408 Peoples R China

On the Loess Plateau of China, the number of projects involving the excavation of mountains and the filling of valleys to create new land is rising. The loess excavated from the mountain is directly used as building material. After being filled into the valley and remolded, it serves as the foundation for overlying structures. However, significant differences in mechanical behavior exist between intact and remolded loess, leading to various issues such as differential settlement. Understanding the microstructure of loess is essential for improving our comprehension of its macro-level hydrological and mechanical behavior. Due to the inherent limitation of the conventional methods (e.g., scanning electron microscopy and mercury intrusion porosimetry) for microstructure investigation, an in-depth understanding of the three-dimensional (3D) microstructural differences between intact and remolded loess remains elusive. To address this gap, this study employs advanced X-ray micro-computed tomography (micro-CT) to investigate the 3D microstructure of both intact and remolded loess from two typical man-made new land creation projects. The three-dimensional microstructures are segmented into a series of cubes of varying dimensions to identify the structure's representative volume element (RVE) and assess the uniformity of both loess types. The pore network of the RVE is quantitatively analyzed to characterize the microstructure. The results reveal significant disparities between the microstructure of intact and remolded loess, particularly in terms of uniformity, pore size distribution, and pore connectivity. Remolded loess exhibits a denser structure with poorer pore connectivity and greater heterogeneity compared to intact loess. These microstructural differences are attributed to the distinct formation processes of the two types of loess.

关键词： three-dimensional microstructure micro-CT representative volume element intact loess remolded loess

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three-dimensional microstructure modeling of particulate composites using statistical synthetic structure and its thermo-mechanical finite element analysis

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COMPUTATIONAL MATERIALS SCIENCE 2017年 126卷 265-271页

作者： Park, Hyung Keun Jung, Jaimyun Kim, Hyoung Seop Pohang Univ Sci & Technol POSTECH Dept Mat Sci & Engn Pohang 37673 South Korea Pohang Univ Sci & Technol POSTECH Ctr High Entropy Alloys Pohang 37673 South Korea

The mechanical and thermal properties of a particulate composite are generally dependent on its microstructure. In the present work, statistical synthetic structures are built to represent three-dimensional microstructure of SiC particle-reinforced Al composites. The statistical parameters are referred to the previous literature and our experimental data. Thermo-mechanical finite element analysis is performed to predict the Young's modulus and thermal expansion coefficient, which are in good agreement with the experimental results. Furthermore, the irregular distribution of stress and strain from statistical synthetic models provides better qualitative description compared to other artificially synthesized models, such as unit cell models. Considering the accuracy, flexibility, and cost of the statistical synthetic model, we confirm that this model has high potential as an efficient modeling scheme for a wide range of materials. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Synthetic structure Statistical parameter Finite element method three-dimensional microstructure Thermomechanical properties

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three-dimensional microstructure of the bone in a hamster model of senile osteoporosis

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BONE 2008年第3期43卷 494-500页

作者： Chen, Huayue Zhou, Xiangrong Washimi, Yuki Shoumura, Shizuko Gifu Univ Grad Sch Med Dept Anat Gifu 5011194 Japan Gifu Univ Grad Sch Med Dept Intelligent Image Informat Gifu 5011194 Japan Fujita Hlth Univ Dept Orthopaed Surg Toyoake Aichi 4701192 Japan Chubu Gakuin Univ Fac Rehabil Dept Phys Therapy Gifu 5013993 Japan

Age-related bone loss, which is poorly characterized, is a major underlying cause of osteoporotic fractures in the elderly. In order to identify the morphological feature of age-related bone loss, we investigated sex and site (tibia, femur and vertebra) dependence of bone microstructure in aging hamsters from 3 to 24 months of age using micro-CT. In the proximal tibia and distal femur, trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (***) and bone mineral density (BMD) increased to a maximum at 6 or 12 months and then declined progressively from 12 to 24 months of age. Trabecular separation (***), trabecular bone pattern factor (TBPO and structure model index (SMI) increased with age. As compared with male hamsters, BV/TV and Tb.N were significantly lower in females at 18 and 24 months of age. Age-related decrease of trabecular BV/TV in the vertebral body was less than that of the femoral and tibial metaphyses. In the mid-femoral diaphysis, cortical bone area remained constant from 3 to 24 months of age. Cortical thickness decreased from 12 to 24 months and cortical BMD declined significantly from 18 to 24 months of age. These findings indicate that skeletal site and sex differences exist in hamster bone structure. Age-related bone changes in hamsters resemble those in humans. We conclude that hamster may be a useful model to Study at least some aspects of bone loss during human aging. Crown Copyright (C) 2008 Published by Elsevier Inc. All rights reserved.

关键词： aging bone structure hamster micro-CT three-dimensional microstructure

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three-dimensional microstructure of thin copper foils revealed by ion beam cutting and electron backscatter diffraction (EBSD)

Three-dimensional microstructure of thin copper foils reveal...

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2nd International Conference on Texture and Anisotropy of Polycrystals

作者： Simons, G Kunze, K Hauffe, W Dual, J ETH Inst Mechan Syst Mech CH-8092 Zurich Switzerland ETH Inst Geol CH-8092 Zurich Switzerland Tech Univ Dresden Inst Festkorperphys D-01062 Dresden Germany

ISBN: (纸本)3908451094

Tensile testing of thin rolled copper foils with thickness ranging from 10 to 250 mu m shows a dependence of the fracture strain with respect to the thickness of the foils [G. Simons et al., in Solid Mechanics and its Applications, Vol. 114 (2004), pp. 89-96]. To understand the influence of the microstructure in the foils on this phenomenon the microtexture is investigated by orientation mapping through electron backscatter diffraction (EBSD). As the samples are rather small standard preparation techniques do not apply. Two methods are described which allow the investigation of different section cuts of the samples: Cross sections of the samples were produced by ion beam cutting with a wide beam of 7 keV Kr ions. Internal planes parallel to the specimen surface were made accessible by wet etching. The as-received material possesses a very strong texture consisting mostly of the cube component and some remnants of a previous rolling texture. Specimens tested in a tensile test do not show major microstructural changes compared to virgin samples. After a heat treatment at 300 degrees C the cube texture has significantly weakened in favour of revived rolling components, and the fracture strain increased about ten times relative to the as-is material.

关键词： thin Copper foils EBSD three-dimensional microstructure tensile testing

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Permeability of loess from the South Jingyang Plateau under different consolidation pressures in terms of the three-dimensional microstructure

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BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT 2020年第9期79卷 4841-4857页

作者： Wei, Ya-ni Fan, Wen Yu, Ningyu Deng, Long-sheng Wei, Tingting Changan Univ Sch Geol Engn & Geomat 126 Yanta Rd Xian 710054 Shaanxi Peoples R China

Multiple consolidation-permeability tests were performed on loess samples from the South Jingyang Plateau in northwest China to analyze permeability under actual stresses. three-dimensional microstructures for loess samples under each consolidation stress were established based on high-resolution computed tomography images to thoroughly interpret the permeability variation in terms of the loess microstructures including the pores and throats. With increasing consolidation pressure, the permeability decreased greatly at the beginning and tended to become stable. In the stage of dramatic decrease in permeability, pore coordination number decreased slightly under pressure, indicating little influence of connectivity among pores on permeability. The pores in the range of 14 to 25 mu m decreased by 10.1% in volume percentage, and the pores larger than 13 mu m decreased by 19.6% in number. Accordingly, throats larger than 6 mu m decreased by 13.1% in area percentage, and throats larger than 2 mu m decreased by 14.9% in number. Throat size distribution played a decisive role in permeability, pore size distribution acted as a bridge to influence permeability, and only the spaced pores and some interaggregate or intergrain pores larger than 13 mu m that allowed free water to pass were related to permeability. The decreases in these relatively large pores and throats caused considerable decreases in permeability. However, the existence of large throats, even large numbers of such throats, does not mean high permeability, which can be verified in the stable stage of permeability. This research provides a better understanding of loess permeability in terms of three-dimensional microstructure and further insights into the stability analysis of loess slopes and the control of other hazards in loess regions.

关键词： South Jingyang Plateau Loess permeability three-dimensional microstructure Pore and throat size distribution

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three-dimensional microstructure characterization of loess based on a serial sectioning technique

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ENGINEERING GEOLOGY 2019年 261卷 105265-000页

作者： Wei, Tingting Fan, Wen Yu, Ningyu Wei, Ya-ni Changan Univ Sch Geol Engn & Geomat 126 Yanta Rd Xian 710054 Shaanxi Peoples R China Minist Educ Key Lab Western Chinas Mineral Resources & Geol E 126 Yanta Rd Xian 710054 Shaanxi Peoples R China China Elect Res Inst Engn Invest & Design Xian 710054 Shaanxi Peoples R China

Loess has a loose metastable structure that easily collapses during wetting and loading. microstructure analysis is essential for a better understanding of the engineering properties of loess;however, two-dimensional (2D) methods cannot fully demonstrate the geometric microstructural characteristics of loess particles. The three-dimensional (3D) loess microstructure is reconstructed based on an improved serial sectioning technique. Point, edge and face contacts are observed from the 3D reconstructed microstructure of natural loess. The 3D microstructural features of particles and pores are also quantitatively studied by analyzing statistical parameters, including the equivalent diameter, sphericity, aspect ratio and orientation index. The particle size distribution (> 10 mu m) obtained from the microstructural analysis is validated via a comparison with the results of a laser particle size analysis. In total, 92% of the particles have a sphericity that lies between 0.5 and 0.9, and the aspect ratio of 93% of the particles is between 0.3 and 0.7. Additionally, 67% of the particles are oriented from 0 degrees to 45 degrees, whereas approximately 64% of the pores (> 2 mu m) are oriented from 45 degrees to 90 degrees. Each 3D parameter has a unique value and can reflect the true spatial morphology of the particles, avoiding the influence of the observation angle and section. The 3D characterization of the loess microstructure will provide insights into the underlying collapse mechanisms and could provide realistic 3D parameters for use in numerical simulations.

关键词： Loess three-dimensional microstructure Serial sectioning technique Quantitative analysis

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A Novel three-dimensional microstructure Fabrication Method Based on Multilevel Imprint Lithography

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CHINESE JOURNAL OF ELECTRONICS 2009年第4期18卷 583-587页

作者： Wang Quandai Duan Yugang Lu Bingheng Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian 710049 Peoples R China

A 3D layered fabrication process based on Multilevel imprint lithography (MIL) is proposed and the critical issues involving template fabrication and overlay accuracy were investigated. A fast and low-cost template fabrication process based on glass wet etching is introduced, in which, the etching mask of Cr metal film is partially remained on top of the template pattern protrusion after etching, which facilitates the residual resist removal and pattern quality improvement. An imprint tool with an alignment subsystem based on computer micro-vision is developed and the experimental results show an average overlay accuracy within 1.5 mu m with a standard deviation within 0.33 mu m. Finally, as an instance of the proposed method, the process based on MIL, electroplating and liftoff was investigated and tri-layer metallic structures with a pattern feature size of 20 mu m were fabricated using the optimized process, which demonstrates the feasibility of the layered fabrication method.

关键词： three-dimensional microstructure Layered fabrication Multi-level imprint lithography MEMS

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Electrically conductive graphene-filled polymer composites with well organized three-dimensional microstructure

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MATERIALS LETTERS 2014年 121卷 74-77页

作者： Zhao, Pengfei Luo, Yongyue Yang, Junlong He, Dongning Kong, Lingxue Zheng, Peng Yang, Qi Sichuan Univ State Key Lab Polymer Mat Engn Coll Polymer Sci & Engn Chengdu 610065 Peoples R China Chinese Acad Trop Agr Sci Agr Prod Proc Res Inst Chinese Agr Minist Key Lab Trop Crop Prod Proc Zhanjiang 524001 Peoples R China Deakin Univ Inst Frontier Mat Waurn Ponds Vic 3216 Australia

Electrically conductive graphene-filled polystyrene nanocomposites with well-organized three dimensional (3D) microstructures were simply prepared by electrostatic assembly integrated latex technology. First, positively charged polystyrene was synthesized via disperse polymerization in ethanol/water medium by using a cationic co-monomer, and then directly co-assembled with graphene oxide. Eventually, a honeycomb-like graphene 3D framework was embedded in polystyrene matrix after in situ chemical reduction and hot compression molding. Due to the 3D conductive pathway derived from graphene based network evidenced by morphology studies, the fabricated nanocomposites Show excellent electrical properties, i.e. extremely low percolation threshold of 0.09 vol% and high saturated conductivity of 25.2 S/m at GNs content of 1.22 vol%. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Electrical property Graphene Polymers Nanocomposites three-dimensional microstructure

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three-dimensional microstructure characteristics and evolution on dentin surface induced by ultraviolet laser irradiation

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JOURNAL OF LASER APPLICATIONS 2013年第4期25卷 042002-042002页

作者： Li, Qiurui Ji, Lingfei Chen, Xiaochuan Jiang, Yijian Beijing Univ Technol Inst Laser Engn Beijing 100124 Peoples R China

In texturing dentin surface by KrF laser with the fluences of 200-800 mJ/cm(2), it is observed the irradiated surface topography has different characteristics with that irradiated under high fluence above 1000 mJ/cm(2) reported in previous studies. The formation threshold fluence of the microstructure consisted of erected microcylinders was determined at 400 mJ/cm(2). By scanning electron microscopy including fine examination of a single microstructure unit under high magnification, the microstructure formation and evolution tending to the fashion of high fluence were given. Analysis of the ablation details captured by high-speed photography confirmed the development mechanism of the texturing microstructure. Raman analysis showed the composition of the laser textured dentin underwent changes. Although the texturing is related to the characteristics of the dentin tissue, laser parameters play a decisive role in the controlling of the shape and the height of the three-dimensional microstructure. The combination of our work and the previous work by Sivakumar et al. [J. Laser Appl. 18(4), 330-333 (2006) and Lasers Med. Sci. 21, 160-164 (2006)] demonstrates laser fabrication of the three-dimensional microstructure with different topography features on dentin surface is controllable. (C) 2013 Laser Institute of America.

关键词： laser ablation three-dimensional microstructure dentin

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Age- and gender-dependent changes in three-dimensional microstructure of cortical and trabecular bone at the human femoral neck

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OSTEOPOROSIS INTERNATIONAL 2010年第4期21卷 627-636页

作者： Chen, H. Zhou, X. Shoumura, S. Emura, S. Bunai, Y. Gifu Univ Grad Sch Med Dept Anat Gifu 5011194 Japan Gifu Univ Grad Sch Med Dept Intelligent Image Informat Gifu 5011194 Japan Chubu Gakuin Univ Sch Rehabil Dept Phys Therapy Gifu 5013993 Japan Gifu Univ Sch Med Nursing Course Gifu 5011194 Japan Gifu Univ Grad Sch Med Dept Legal Med Gifu 5011194 Japan

We investigated age- and gender-related variation of both cortical and trabecular microstructure in human femoral neck. We found that age-related change of cortical porosity is more noticeable than that of trabecular parameter. Our data may help to gain more insight into the potential mechanism of osteoporotic femoral neck fractures. Variations in the microstructure of cortical and trabecular bone contribute to decreased bone strength. Age- and gender-related changes in cortical and trabecular microstructure of femoral neck is unclear. The aim of this study was to identify three-dimensional (3D) microstructural changes of both cortical and trabecular bone simultaneously in human femoral neck with age and gender, using micro-computed tomography (micro-CT). We hypothesized that there would be differences in age-related changes of cortical and trabecular bone for both women and men. We used 56 femoral necks of 28 women and men (57-98 years of age) from a Japanese population. The subjects were chosen to give an even age and gender distribution. Both women and men were divided into three age groups: middle (57-68 years), old (72-82 years), and elderly (87-98 years) groups. We examined cortical bone specimen from the inferior sector of femoral neck and trabecular bone specimen from the middle of femoral neck using micro-CT and 3D bone analysis software. Cortical thickness (***) decreased by 10-15%, cortical porosity (Ca.V/TV) almost doubled, and canal diameter (***) increased by 65-77% between the middle-aged and elderly groups for both women and men. The trabecular bone volume fraction (BV/TV) decreased by around 20%;trabecular thickness (***), trabecular number (Tb.N), and connectivity density (Conn.D) decreased;and trabecular separation (***) and structure model index (SMI) increased with age for both women and men. As compared with women, men had higher *** and BV/TV and lower Ca.V/TV and *** among three age groups. There was a significant inverse correlat

关键词： Aging Cortical porosity Femoral neck Micro-CT three-dimensional microstructure Trabecular bone

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