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Size effects on springback behavior of H80 foils

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Rare Metals 2018年第12期37卷 1082-1090页

作者： Zhen-Wu Ma Zi-Yang Cao Jin-Bin Lu yuan-jing zhang Wei Liu Zhen Yin College of Mechanical Engineering Suzhou University of Science and TechnologySuzhou 215009China Suzhou Key Laboratory of Precision and Efficient Machining Technology Suzhou 215009China

Size effects make traditional bending theories infeasible in analyzing the springback behavior of H80 foils in the similarity bending experiment. It is observed that there is a certain critical thickness value, which divides the change trend of springback amount of foils into two opposite parts. In order to reveal the reason for size effects on the springback behavior of H80 foils, the method of hardness increment characterization was applied to describe the deformation distribution of foils. The competition between strengthening effect of geometrically necessary dislocations and weakening effect of surface grains determines the change trend of springback amount with foil thickness. When the thickness of foils is large, the weakening effects dominate the material behavior, resulting in that the springback amount decreases with the decrease in foil thickness. However, when the foil thickness is small, the strengthening effects dominate the springback tendency, leading to a sharp increase in the springback amount. Furthermore, the deformation distribution is disturbed due to the enhanced effects of individual grain heterogeneity with the decrease in the thickness of foils, leading to the large scatter of springback angle after unloading.

关键词： Foil bending Springback behavior Size effects Hardness increment characterization

Synthesis of a Novel Core-shell Type Acrylic-polyurethane Hybrid Emulsion Containing Siloxane and Fluorine as well as Water and the Oil Resistances of Cured Film

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Chinese Chemical Letters 2006年第8期17卷 1121-1124页

作者： jing CHAO Xing yuan zhang Jia Bing DAI Zhen GE Lin Lin FENG Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230026

Siliconated polyurethane （Si-PU） was synthesized using isophorone diisocyanate （IPDI）, hydroxybutyl-terminated polydimethylsiloxane （PDMS）, polytetramethylene ether glycol （PTMG）, polypropylene glycol （PPG）, 1,6-hexanediol （HDO）, dimethylol propionic acid （DMPA） and triethylamine （TEA）. Based on butyl acrylate （BA）, 2, 2, 2-trifluoroethylmethacrylate （TFEMA） and Si-PU as a seed emulsion, a novel core-shell type acrylic-polyurethane hybrid emulsion, containing siloxane and fluorine （F-Si-PU）, was prepared by seeded emulsion polymerization. The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy （FTIR） was used to identify the chain structures of Si-PU and F-Si-PU. Investigation of transmission electron microscopy （TEM） confirmed the core-shell structure of F-Si-PU emulsion. Measurement results of water contact angle and the swelling ratio in water and n-octane for cured film showed that the water and the oil resistances for F-Si-PU had been significantly improved at a suitable content of fluorine and siloxane.

关键词： Core-shell siloxane fluorine acrylic-polyurethane water and oil resistance.

Impact of Carbon Chain Structures in the Backbone on the Flexibility of Modified Polyarylene Sulfide Resins: Molecular Dynamics Simulations and Mesoscopic Analysis

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Chinese Journal of Polymer Science 2024年第4期42卷 544-557页

作者： Chi zhang Rong Liu jing-yuan Liu Wen-Wei Jiang Key Laboratory of Fine Chemical Engineering and Functional Materials School of Chemical EngineeringSichuan UniversityChengdu610065China

In the domain of high-performance engineering polymers, the enhancement of mechanical flexibility in poly(phenylene sulfide) (PPS) resins has long posed a significant challenge. A novel molecular structure, designated as PP-He-IS, wherein imide rings and an aliphatic hexylene chain are covalently incorporated into the PPS backbone to enhance its flexibility, is introduced in this study. Molecular dynamics (MD) simulations are employed to systematically explore the effects of diversifying the backbone chain structures by substituting phenyl units with alkyl chains of varying lengths, referred to as PP-A-IS where “A” signifies the distinct intermediary alkyl chain configurations. Computational analyses reveal a discernable decrement in the glass transition temperature (Tg) and elastic modulus, counterbalanced by an increment in yield strength as the alkyl chain length is extended. Notably, the PP-He-IS variant is shown to exhibit superior yield strength while simultaneously maintaining reduced elastic modulus and Tg values, positioning it as an advantageous candidate for flexible PPS applications. Mesoscopic analyses further indicate that structures such as PP-He-IS, PP-Pe-IS, and PP-Bu-IS manifest remarkable flexibility, attributable to the presence of freely rotatable carbon-carbon single bonds. Experimental validation confirms that a melting temperature of 504 K which is lower than that of conventional PPS, and lower crystallinity are exhibited by PP-He-IS, thereby affording enhanced processability without compromising inherent thermal stability. Novel insights into the strategic modification of PPS for mechanical flexibility are thus furnished by this study, which also accentuates the pivotal role played by molecular dynamics simulations in spearheading high-throughput investigations in polymer material modifications.

关键词： Molecular dynamics simulations Polyarylene Sulfide Main-chain modifications Flexibility Aliphatic hexylene chain

Solvothermal synthesis and adsorption performance of layered boehmite using aluminum chloride and high-alumina fly ash

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Chinese Journal of Chemical Engineering 2024年第6期70卷 280-290页

作者： jing Wen Ruirui yuan Tao Jiang Tangxia Yu Yufan zhang School of Metallurgy Northeastern UniversityShenyang 110819China Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China Liaoning Key Laboratory for Metallurgical Sensor and Technology Shenyang 110819China

High alumina fly ash(FAHAl)is a kind of bulk solid waste unique to China,whose availability of high-value aluminum and the threat to the environment makes its high-value utilization *** this work,the alumina containing leaching solution obtained from Na_(2)CO_(3) roasting and HCl leaching of FAHAl was used as the mother liquor to prepare layered boehmite in *** preparation process with AlCl_(3) as the raw material was also *** formation process and mechanism of boehmite,the choice of solvent,along with the adsorption capability of Congo red were analyzed by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,Brunauer-Emmett-Teller method and adsorption *** showed that during the preparation of layered boehmite,the precursor Al(OH)_(3) from the reaction of Al^(3+) and OH-is transformed into boehmiteγ-*** existence of ethanol is beneficial to regulate and promote the growth of boehmite crystal *** water and ethanol are mixed with a volume ratio of 2:1 and used as the solvent,the maximum specific surface area of the boehmite is obtained at 135.7 m^(2)·g^(-1),and 99.16%of Congo red can be absorbed after 10 min when AlCl3 is used as a raw *** purified leaching solution is used as the mother liquid,the crystallinity of boehmite decreases slightly when the pH value decreases from 12.5 to *** pH is 11,the removal efficiency of Congo red reaches a maximum of 72.25%.This process not only achieves the extraction of aluminum and high-value utilization of FAHAl but also provides a thought to prepare layered boehmite with adsorption properties.

关键词： High-alumina fly ash Layered boehmite In-situ preparation Solvothermal synthesis Adsorption High-value utilization

Material flow behavior modeling with consideration of size effects

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Rare Metals 2018年第11期37卷 995-1002页

作者： Zhen-Wu Ma Zi-Yang Cao Jin-Bin Lu Hua Li yuan-jing zhang Wei Liu Zhen Yin College of Mechanical Engineering Suzhou University of Science and TechnologySUzhou 215009China Suzhou Key Laboratory of Precision and Efficient Machining Technology Suzhou 215009China

Size effects make traditional forming theories infeasible in analyzing the micro-forming process, so it is necessary to develop an accurate material model to describe the material flow behavior with consideration of size effects. By studying the size effects of the flow behavior of H80 foils experimentally, it is found that the foil flow stress and strain hardening ability reduce significantly with the decrease of foil thickness. The reduction of the proportion of internal grains which own complete grain boundaries is the main cause of size effects of foil flow behavior. Moreover, grain refinement can reduce the size effects on material flow behavior. On these bases, a phenomenological material model has been developed to mathematically describe the material flow behavior with consideration of the effects of geometry size, grain size and strain hardening behavior. The reasonability and accuracy of this new model are verified by comparing the calculation values with experimental results in metal foil tensile and micro-bulk upsetting experiments. These experimental results and the proposed model lay a solid foundation for understanding and further exploring the material flow behavior in the micro-forming process.

关键词： Size effects Internal grains Material behavior Modeling

On Robust Cross-view Consistency in Self-supervised Monocular Depth Estimation

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Machine Intelligence Research 2024年第3期21卷 495-513页

作者： Haimei Zhao jing zhang Zhuo Chen Bo yuan Dacheng Tao School of Computer Science University of SydneySydney2008Australia Shenzhen International Graduate School Tsinghua UniversityShenzhen518055China School of Information Technology&Electrical Engineering University of QueenslandBrisbane4072Australia

Remarkable progress has been made in self-supervised monocular depth estimation (SS-MDE) by exploring cross-view consistency, e.g., photometric consistency and 3D point cloud consistency. However, they are very vulnerable to illumination variance, occlusions, texture-less regions, as well as moving objects, making them not robust enough to deal with various scenes. To address this challenge, we study two kinds of robust cross-view consistency in this paper. Firstly, the spatial offset field between adjacent frames is obtained by reconstructing the reference frame from its neighbors via deformable alignment, which is used to align the temporal depth features via a depth feature alignment (DFA) loss. Secondly, the 3D point clouds of each reference frame and its nearby frames are calculated and transformed into voxel space, where the point density in each voxel is calculated and aligned via a voxel density alignment (VDA) loss. In this way, we exploit the temporal coherence in both depth feature space and 3D voxel space for SS-MDE, shifting the “point-to-point” alignment paradigm to the “region-to-region” one. Compared with the photometric consistency loss as well as the rigid point cloud alignment loss, the proposed DFA and VDA losses are more robust owing to the strong representation power of deep features as well as the high tolerance of voxel density to the aforementioned challenges. Experimental results on several outdoor benchmarks show that our method outperforms current state-of-the-art techniques. Extensive ablation study and analysis validate the effectiveness of the proposed losses, especially in challenging scenes. The code and models are available at https://***/sunnyHelen/RCVC-depth.

关键词： 3D vision depth estimation cross-view consistency self-supervised learning monocular perception

pH Induced Self-assembly of AIE Fluorescent Probe for Tumor Imaging

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Chinese Journal of Polymer Science 2024年第1期42卷 7-13,I0005页

作者： jing-yuan Xiang Wen-Long zhang He-Ting Li Ya-Ning He Department of Chemical Engineering Key Laboratory of Advanced Materials(MOE)Tsinghua UniversityBejing 100084China

This work reported an AIE fluorescent probe for tumor imaging based on the p H induced self-assembly strategy. The fluorescent probe was composed of an acid-responsive soluble copolymer PEG-b-PAMA-DMMA with a maleic acid amide group and an anionic soluble aggregation-induced emission fluorogen(AIEgen) TPE-2SO_(3)^(-). The polymer could be transformed into a protonated amine-containing polymer after the hydrolysis of maleic acid amide in acidic tumor microenvironment, which would be further self-assembled with TPE-2SO_(3)^(-)to form aggregated nanoparticles. The transition of TPE-2SO_(3)^(-)from dispersed state to aggregated state led to an obvious increase in fluorescence intensity due to its AIE characteristics.

关键词： p H-responsive Self-assembly Fluorescent probe AIE Tumor imaging

Transverse mode-coupling instability with longitudinal impedance

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Nuclear Science and Techniques 2024年第6期35卷 40-53页

作者： Hai-Sheng Xu Chun-Tao Lin Na Wang jing-Ye Xu yuan zhang Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China Institute of Advanced Science Facilities Shenzhen 518107GuangdongChina

Transverse mode-coupling instability(TMCI)is a dangerous transverse single-bunch instability that can lead to severe par-ticle *** mechanism of TMCI can be explained by the coupling of transverse coherent oscillation modes owing to the transverse short-range wakefield(i.e.,the transverse broadband impedance).Recent studies on future circular colliders,e.g.,FCC-ee,showed that the threshold of TMCI decreased significantly when both longitudinal and transverse impedances were *** performed computations for the circular electron-positron collider(CEPC)and observed a similar *** studies on the influence of longitudinal impedance on the TMCI threshold were *** concluded that the imaginary part of the longitudinal impedance,which caused a reduction in the incoherent synchrotron tune,was the primary reason for the reduction in the TMCI ***,the real part of the longitudinal impedance assists in increasing the TMCI threshold.

关键词： Transverse mode-coupling instability Longitudinal impedance

Kinetics insights into size effects of carbon nanotubes'growth and their supported platinum catalysts for 4,6-dinitroresorcinol hydrogenation

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Chinese Journal of Chemical Engineering 2024年第8期72卷 133-140页

作者： Yan zhang Xiangxue zhang Keng Sang Wenyao Chen Gang Qian jing zhang Xuezhi Duan Xinggui Zhou Weikang yuan State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China

Size effects are a well-documented phenomenon in heterogeneous catalysis,typically attributed to alterations in geometric and electronic *** this study,we investigate the influence of catalyst size in the preparation of carbon nanotube(CNT)and the hydrogenation of 4,6-dinitroresorcinol(DNR)using Fe_(2)O_(3)and Pt catalysts,*** Fe_(2)O_(3)/Al_(2)O_(3)catalysts were synthesized for CNT growth through catalytic chemical vapor *** findings reveal a significant influence of Fe_(2)O_(3)nanoparticle size on the structure and yield of ***,CNT produced with Fe_(2)O_(3)/Al_(2)O_(3)containing 28%(mass)Fe loading exhibits abundant surface defects,an increased area for metal-particle immobilization,and a high carbon *** makes it a promising candidate for DNR *** this catalyst support,we further investigate the size effects of Pt nanoparticles on DNR *** Pt catalysts demonstrate a preference for 4,6-diaminoresorcinol generation at(100)sites,whereas smaller Pt catalysts are more susceptible to electronic *** kinetics insights obtained from this study have the potential to pave the way for the development of more efficient catalysts for both CNT synthesis and DNR hydrogenation.

关键词： Kinetics Size effects Catalytic hydrogenation Active site