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58th US Rock Mechanics / Geomechanics Symposium 2024, ARMA 2024

作者： Xu, Z. Li, W. Kolanti, A. Sprouster, D. Department of Civil Engineering Stony Brook University Stony BrookNY United States Department of Material Science and Chemical Engineering Stony Brook University Stony BrookNY United States

ISBN: (纸本)9798331305086

Flow and dissolution induce wormholes in porous rocks, which lead to a substantial increase in both permeability and flow heterogeneity of the rock formation. Wormholes originate from the initial micron-scale pore networks, and gradually transition to more prominent millimeter-scale holes. Wormholes have a crucial impact on the flow and reactions in subsurface technologies, such as critical mineral leaching, CO2 storage and reservoir stimulation. Understanding how wormholes form from pore networks is crucial for the effectiveness of these subsurface technologies. However, current studies are limited to two separate scales of characterizations: millimeter-scale wormholes and micron-scale pore networks. The transitional region, which bridges these features at the two scales, remains largely unexplored and inadequately characterized. This knowledge gap obscures our understanding of the underpinning physics that governs wormhole formation in porous rocks. In this study, we aim to bridge these two scales of study with multiscale characterization. We create wormholes in porous gypsum specimens through core flood tests. The wormholes are then scanned with low-resolution (26.70 µm) and high-resolution (3.43 µm) X-ray computed tomography (CT). We quantitatively characterize the geometry of the wormholes leading to pore networks regarding their diameters, and quantities. This 3D cross-scale characterization allows for an accurate depiction of the interactions between wormholes and pore networks and provides physical insights into the initiation of wormholes. Copyright 2024 ARMA, American Rock Mechanics Association.

关键词： Rock mechanics

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Mechanically robust antifouling coating with dual-functional antifouling strategy by infiltrating PDMS into plasma-sprayed porous Al_(2)O_(3)-Cu coating

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Journal of materials science & Technology 2023年第28期159卷 125-137页

作者： Shuaiqiang Bi Kangwei Xu Guosheng Shao Ke Yang Jiajia Tian State Centre for International Cooperation on Designer Low-Carbon and Environmental Material(SCICDLCEM) School of Materials Science and EngineeringZhengzhou UniversityZhengzhou450001China Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou450001China Special Functional Materials Department Luoyang Ship Material Research InstituteLuoyang471023China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

Marine biofouling is a worldwide challenge that needs to be solved ***(dimethylsiloxane)(PDMS)-based fouling release coatings with low surface free energy(SFE)could effectively inhibit ***,their poor mechanical durability,adhesive strength,and antifouling performance under static conditions significantly limit their ***,a novel mechanically robust Al_(2)O_(3)-PDMS-Cu composite coating with strong adhesive strength and remarkable antifouling performance was *** Al_(2)O_(3)-PDMS-Cu coating loaded with a small amount of Cu was fabricated by infiltrating PDMS into plasma-sprayed micro/nano-scaled porous Al_(2)O_(3)-Cu *** showed that the fabri-cation of this Al_(2)O_(3)-PDMS-Cu coating did not alter the surface hydrophobicity and SFE of PDMS signif-icantly,thus presenting little influence on its inherent fouling release *** rigorous abrasion test,the Al_(2)O_(3)-PDMS-Cu coating presented remarkably improved surface hydrophobicity due to the ex-posure of micro/nano structure,rather than falling offas that of PDMS *** combination of excel-lent abrasion resistance and one order of magnitude higher adhesive strength and hardness than PDMS coating contributed to the outstanding mechanical robustness of Al_(2)O_(3)-PDMS-Cu ***,the antifouling assays against marine bacteria adhesion(95%reduction rate for Escherichia coli.(***))and algae attachment(96%and 94%reduction rates for Chlorella and Phaeodactylum tricornutum(***-nutum),respectively after 21 days of incubation)demonstrated the superior antifouling performance of the Al_(2)O_(3)-PDMS-Cu ***,a high-performance Al_(2)O_(3)-PDMS-Cu antifouling coating with excellent mechanical robustness and long-term antifouling performance was achieved via the combination of me-chanical durability of Al_(2)O_(3)skeleton and the dual-functional antifouling strategy,i.e.,the fouling release property of PDMS and fouling r

关键词： Marine antifouling Al_(2)O_(3)-PDMS-Cu composite coating Plasma spraying Mechanical robustness Dual-functional strategy Long-lasting antifouling

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Investigation of the Thermal and Mechanical Properties of Hydrolyzed-Collagen-Reinforced Poly(lactic acid) Composite Blown Films

ACS Sustainable Resource Management

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ACS Sustainable Resource Management 2024年第1期2卷 62-71页

作者： Radhika Panickar Vijay K. Rangari Department of Material Science and Engineering Tuskegee University Tuskegee Alabama 36088 United States

Poly(lactic acid) (PLA) is a biodegradable polyester polymer that is a promising material for replacing petroleum-based polymers in various applications. The present study investigates the mechanical and thermal properties of hydrolyzed collagen (HC) powder-reinforced biopolymer composite blown films. The biodegradable polymer PLA was reinforced with HC at different weight percentages (0.5%, 0.75%, 1%, and 1.25%) using the solution blending method in chloroform, followed by blown-film extrusion. Among different weight percentages of HC in the PLA matrix, 1 wt % HC reinforced with PLA blown films exhibited significant changes and improvements in the FTIR, XRD, TGA, and DSC analyses. A polymer blend formation from PLA and 1% HC was observed in XRD, FTIR, and Raman analyses, exhibiting chemical bonding of the amide group to the PLA backbone. It was understood that intermolecular interaction of the PLA and HC molecules was due to the inter-H bonds of the −NH, −OH, and −CH functional groups. The thermal behavior and crystallinity of the PLA/HC composite films were investigated using TGA and DSC. Compared with other film samples, PLA/1% HC exhibited a higher thermal stability of 360.29 °C. The tensile studies show significant enhancement in the flexibility with a high elongation strength of PLA/HC composite films compared to neat PLA films. The fracture analysis of PLA/1% HC confirms the interfacial compatibility and transformation to plastic deformation due to the chemical bonding of HC in the PLA matrix. The PLA/HC composite films exhibit UV barrier properties that are recommended for food packing applications.

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Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

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Defence Technology（防务技术） 2024年第9期39卷 203-216页

作者： Zhonggang Li Longmiao Chen Yifan Li Yufeng Jia Quan Zhang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Technology Center Shanxi North Machine-building Co.Ltd.Taiyuan 030009China Research and Development Department Kelong New Material Technology Co.Ltd.Xianyang 712000China

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism,made of polychloroprene rubber(PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar(SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects;meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing.

关键词： Breech mechanism Gas obturator Polychloroprene rubber Constitutive model Strain rate Damage

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Improving the Accuracy of Animal Species Classification in Camera Trap Images Using Transfer Learning

Improving the Accuracy of Animal Species Classification in C...

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2024 International Conference on Artificial Intelligence, Computer, Data sciences, and Applications, ACDSA 2024

作者： Boukar, Moussa Mahamat Mahamat, Assia Aboubakar Djibrine, Oumar Hassan Abubakar, Usman Bello Nile University of Nigeria Department of Computer Science Abuja Nigeria Université Virtuelle du Tchad Department of Computer Science Abuja Nigeria African University of Science and Technology Department of Material Science & Engineering Abuja Nigeria Université Virtuelle du Tchad Department of Computer Science N'Djamena Chad Baze University Department of Computer Science Abuja Nigeria

ISBN: (纸本)9798350394528

Understanding biodiversity, monitoring endangered species, and estimating the possible effect of climate change on particular regions all rely on animal species identification. Closed-circuit television (CCTV) cameras, which can collect huge volumes of video data, are an excellent environmental monitoring tool. However, manually evaluating these massive datasets is time-consuming, difficult, and expensive, emphasizing the need for automated ecological *** learning models have transformed computer vision, handling problems such as object and species detection. Their cutting-edge performance qualifies them for this application. The purpose of this work was to create and test machine learning models for distinguishing diverse animal species using camera trap images. On VGG19, GoogLeNet (InceptionV3), ResNet50, and DenseNet121, we used transfer learning. The best multi-classification accuracy was attained by GoogLeNet (87%), followed by ResNet50 (83%), DenseNet (81%), and VGG19 (53%). This evidence suggests that transfer learning outperforms training models from scratch for this task. © 2024 IEEE.

关键词： Image classification

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Measuring surface energy of solid surfaces using centrifugal adhesion balance

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Physical Review E 2024年第1期110卷 014801-014801页

作者： Appu Vinod Yuval Barak Sakshi Yadav Schmid Semih Gulec Yagnavalkya Bhimavarapu Akash Jena David Katoshevski Nitsa Haikin Rafael Tadmor Department of Mechanical Engineering Materials Transformation Material Science and Engineering Dan F. Smith Department of Chemical Engineering Department of Physics

The standard way to evaluate the solid surface energy using probe liquids relies on contact angle measurements. The measured contact angles rely on visible means and are different from their nanoscopic thermodynamic values. This compromises the surface-energy predictions so much that the surface energy-values can be hundreds of percentages higher than expected based on comparisons with different methods as reported in several studies. We consider the Owen-Wendt approach, which breaks the surface energy to polar and dispersive components, and present a technique for measuring surface energy of solids using probe liquids. Our method avoids the need to measure contact angles; instead, it uses solid-liquid work of adhesion measurements which are performed using a centrifugal adhesion balance. In agreement with the studies mentioned above, we found that indeed, the surface energies of the measured solids are significantly lower than those based on contact angle measurements. More importantly we found that our method results in a reasonable breakdown of the surface energy to polar and dispersive components with a higher polar component for more polar solids. This is in contrast with the surface energy based on contact angle measurements for which the breakdown did not make sense, i.e., the measurements reflected higher polar components of the surface energy for less polar solids.

关键词： Adhesives Coatings

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Advanced oxidation via the synergy of C-defective/C-O band modified ultrathin porous g-C_(3)N_(4)and PMS for efficient photothermal degradation of bisphenol pollutants and lignin derivatives

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Green Energy & Environment 2024年第7期9卷 1159-1170页

作者： Liquan Jing Meng Xie Yuanguo Xu Chun Tong Xia Du Heng Zhao Na Zhong Huaming Li Jinguang Hu School of Chemistry and Chemical Engineering Jiangsu UniversityZhenjiang212013China Department of Chemical and Petroleum Engineering University of Calgary2500 University DriveNWCalgaryAlbertaT2N1N4Canada School of Pharmacy Jiangsu UniversityZhenjiang212013China School of Material Science&Chemical Engineering Harbin University of Science and TechnologyHarbin150080China Institute for Energy Research Jiangsu UniversityZhenjiang212013China

This work uses thermal polymerization of urea nitrate,oxyacetic acid and urea as the raw material to prepare ultra-thin porous carbon nitride with carbon defects and C-O band(OA-UN-CN).Density functional theory(DFT)calculations showed OA-UN-CN had narrower band gap,faster electron transport and a new internal construction electric ***,the prepared OA-UN-CN significantly enhanced photocatalytic activation of peroxymonosulfate(PMS)due to enhanced light absorption performance and faster electron *** the result,the OA-UN-CN/PMS could entirely degrade bisphenol A(BPA)within 30 min,where the photodegradation rate was 81.8 and 7.9 times higher than that of g-C_(3)N_(4)and OA-UN-CN,***,the OA-UN-CN/PMS could likewise degrade other bisphenol pollutants and sodium lignosulfonate *** suggested possible photocatalytic degradation pathways accordingly and explored the toxicity of its degradation *** work provides a new idea on the development of advanced photocatalytic oxidation processes for the treatment of bisphenol pollutants and lignin derivatives,via a metal-free photothermal-catalyst.

关键词： Photothermal-catalytic G-C_(3)N_(4) Peroxymonosulfate Bisphenol Sodium lignosulfonate

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A review on flexibility of free bending forming technology for manufacturing thin-walled complex-shaped metallic tubes

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International Journal of Lightweight materials and Manufacture 2023年第2期6卷 165-188页

作者： Abd El-Aty, Ali Guo, Xunzhong Lee, Myoung-Gyu Tao, Jie Hou, Yong Hu, Shenghan Li, Tao Wu, Cong Yang, Qiucheng Department of Materials Science and Engineering & RIAM Seoul National University 1-Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of College of Material Science and Technology Nanjing University of Aeronautics and Astronautics Jiangsu Province Nanjing211106 China Mechanical Engineering Department Faculty of Engineering-Helwan Helwan University Cairo Egypt

Free bending forming (FBF) is a flexible forming technology that gained significant attention recently because of its broad applications in critical industries such as the automotive, aerospace, and nuclear industries. Thus, this paper aims to present a comprehensive review of FBF technology and its flexibility in manufacturing thin-walled complex-shaped metallic tubes with variable curvatures. First, the historical development and state of the art of FBF technology were reviewed and discussed its importance in tube forming recently. Then, the fundamental principles, theoretical modelling, deformation mechanisms during complex bending, critical process parameters, and forming defects with a discussion of the recent research and technological developments of FBF technology under three-, five- and six-axis processes were explained. After that, the system dies and tools design of the FBF machines and the trajectory control of the bending die were presented. Afterwards, the mechanisms of manufacturing spiral and involute hollow metallic tubes and outstanding solutions for critical issues during tube manufacturing, such as springback, cross-section deformation, over-thinning (even cracking), and wrinkling instability were introduced. Finally, the paper is concluded by providing the discussions on the system, die and tool design methodology, and outlook of the FBF technology. © 2022 The Authors

关键词： Bending (forming)

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Construction and Praxis of Six Sigma DMAIC for Bearing Manufacturing Process

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materials Today: Proceedings 2023年 72卷 1426-1433页

作者： Kulkarni, Trishul Toksha, Bhagwan Shirsath, Sagar Pankade, Sandeep Autee, Arun T. Department of Mechanical Engineering Maharashtra Institute of Technology MS Aurangaba 431010 India Maharashtra Institute of Technology Aurangabad 431010 India School of Material Science and Engineering The University of New South Wales Kensington NSW 2052 Australia

The process capability improvement of a bearing manufacturing process using the Six Sigma-DMAIC approach was performed. A progressive method was adopted by the utilization of statistical techniques such as design of experiments for optimizing process capability. We report the draconian improvement in process capability with present approach. This has led to a diminution in high resource spoilage and rework. In the Define-phase, rejection data was used to identify the critical factors responsible for rejection. Process capability indices were used to evaluate the process performance in the Measure-phase. In the Analyze-phase, the vital root causes responsible for low process capability were identified. Using the Taguchi robust design technique, the Improve-phase focuses on optimizing the critical root causes. Analysis of variance was used to examine the results of the experiment. In the control-phase, Cp and Cpk values were improved from 1.170 and 0.976 to 2.780 and 2.230. © 2023

关键词： Six sigma

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Mechanical properties of twin graphene nanotube

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science China Technological sciences 2025年第6期68卷 197-205页

作者： Jianxin LI Hongwei ZHANG Tienchong CHANG Department of Engineering Mechanics School of Ocean and Civil Engineering Shanghai Jiao Tong University School of Urban Planning and Municipal Engineering Xi'an Polytechnic University Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineer Science Shanghai University Shanghai Institute of Aircraft Mechanics and Control Tongji University Joint-Research Center for Computational Material Zhejiang Laboratory

Twin graphene, a novel two-dimensional(2D) semiconducting carbon allotrope, is theorized to exist and may have numerous potential applications due to its superior electronic and mechanical properties. In this study, we propose a new stable nanotube by rolling up twin graphene sheets, referred to as a twin graphene nanotube(TGNT). Molecular dynamics(MD)simulations were performed to investigate the mechanical properties of TGNT under uniaxial tensile loading. It was found that the Young's modulus and failure behavior of TGNTs depend strongly on their intrinsic structure. The Young's modulus decreased with increasing TGNT diameter. The effects of the strain rate, nanotube length, and temperature on the Young's modulus were investigated in detail. These findings provide a fundamental understanding of the mechanical properties of TGNT.

关键词： carbon allotrope twin graphene nanotube molecular dynamics Young’s modulus

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