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3D nano-printed geometric phase metasurfaces for generating accelerating beams with complex amplitude manipulation

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 86-95页

作者： Tianchen Tang Saima Kanwal Yongzheng Lu Yuelong Li Shuangbao Wu Lei Chen Ziheng Qian Zhouyu Xie Jing Wen Dawei Zhang Research Center of Optical Instrument and System Ministry of Education and Shanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China

Metasurface,a forefront in emerging optical devices,has demonstrated remarkable potential for complex amplitude manipulation of light ***,prevailing approaches face challenges in spatial resolution and complexities associated with integrating dynamic phases,impeding the simplified design and reproducible fabrication of ***,we introduce an innovative approach for complex amplitude modulation within 3D nano-printed geometric phase *** approach enables the generation of self-accelerating beams by encoding amplitude through phase-only manipulation,achieving high spatial ***,this method circumvents the conventional need to adjust the geometric parameters of metasurface unit structures for amplitude manipulation,offering a streamlined and efficient route for design and fabrication *** novel methodology holds promise for expedited and low-cost manufacturing of complex amplitude manipulation metasurfaces.

关键词： metasurface complex amplitude manipulation geometric phase 3D nano-printing Airy beam accelerating parabolic beam

Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1858-1864页

作者： Xiaoyu Shi Chongxiao Guo Jiamiao Ni Songsong Yao Liqiang Wang Yue Liu Tongxiang Fan State key lab of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The synthesis of carbide coatings on graphite substrates using molten salt synthesis(MSS),has garnered significant interest due to its cost-effective *** study investigates the reaction process and growth kinetics involved in MSS,shedding light on key aspects of the *** involvement of Ti powder through liquid-phase mass transfer is revealed,where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C content gradient on both sides of the ***,the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer,rather than the chemical reaction *** analyze the kinetics,the thickness of the carbide layer is measured with respect to heat treatment time and temperature,unveiling a parabolic relationship within the temperature range of 700-1300℃.The estimated activation energy for the reaction is determined to be 179283 J·mol^(-1).These findings offer valuable insights into the synthesis of carbide coatings via MSS,facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.

关键词： titanium carbide graphite molten salt kinetic analysis

Reconstruction of particle distribution for tomographic particle image velocimetry based on unsupervised learning method

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PARTICUOLOGY 2024年第10期93卷 349-363页

作者： Zhang, Duanyu Huang, Haoqin Zhou, Wu Feng, Mingjun Zhang, Dapeng Gao, Limin Univ shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Northwestern Polytech Univ Natl Key Lab Aerodynam Design & Res Xian 710072 Peoples R China

The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open acc

关键词： Tomographic particle image velocimetry 3D reconstruction Unsupervised learning Convolutional neural network FLOWS

Novel Partitioned Time-Stepping Algorithms for Fast Computation of Random Interface-Coupled Problems with Uncertain Parameters

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NUMERICAL MATHEMATICS-THEORY METHODS AND APPLICATIONS 2024年第1期17卷 145-180页

作者： Sun, Yizhong Wang, Jiangshan Zheng, Haibiao East China Normal Univ Sch Math Sci Shanghai Peoples R China East China Normal Univ Sch Math Sci Key Lab Math & Engn Applicat Shanghai Key Lab PMMPMinist Educ Shanghai Peoples R China

The simulation of multi-domain, multi-physics mathematical models with uncertain parameters can be quite demanding in terms of algorithm design and computation costs. Our main objective in this paper is to examine a physical interface coupling between two random dissipative systems with uncertain parameters. Due to the complexity and uncertainty inherent in such interface-coupled problems, uncertain diffusion coefficients or friction parameters often arise, leading to considering random systems. We employ Monte Carlo methods to produce independent and identically distributed deterministic heat-heat model samples to address random systems, and adroitly integrate the ensemble idea to facilitate the fast calculation of these samples. To achieve unconditional stability, we introduce the scalar auxiliary variable (SAV) method to overcome the time constraints of the ensemble implicit-explicit algorithm. Furthermore, for a more accurate and stable scheme, the ensemble data-passing algorithm is raised, which is unconditionally stable and convergent without any auxiliary variables. These algorithms employ the same coefficient matrix for multiple linear systems and enable easy parallelization, which can significantly reduce the computational cost. Finally, numerical experiments are conducted to support the theoretical results and showcase the unique features of the proposed algorithms.

关键词： Scalar auxiliary variable ensemble algorithm random interface-coupled problems implicit-explicit partitioned method data-passing partitioned method ENSEMBLE ALGORITHM ERROR ANALYSIS SAV SCHEMES FLOW STABILITY EFFICIENT MODEL

Determination method of mesh size for numerical simulation of blast load in near-ground detonation

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Defence Technology（防务技术） 2024年第8期38卷 111-125页

作者： Doudou Si Zuanfeng Pan Haipeng Zhang College of Civil Engineering Tongji UniversityShanghai 200092China State key lab of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

In order to improve the overall resilience of the urban infrastructures, it is required to conduct blast resistant design for important building structures in the city. For complex terrain in the city, it is recommended to determine the blast load on the structures via numerical simulation. Since the mesh size of the numerical model highly depends on the explosion scenario, there is no generally applicable approach for the mesh size selection. An efficient method to determine the mesh size of the numerical model of near-ground detonation based on explosion scenarios is proposed in this study. The effect of mesh size on the propagation of blast wave under different explosive weights was studied, and the correlations between the mesh size effect and the charge weight or the scaled distance was described. Based on the principle of the finite element method and Hopkinson-Cranz scaling law, a mesh size measurement unit related to the explosive weight was proposed as the criterion for determining the mesh size in the numerical simulation. Finally, the applicability of the method proposed in this paper was verified by comparing the results from numerical simulation and the explosion tests and was verified in AUTODYN.

关键词： Blast load Mesh size effect Numerical simulation Scaled mesh size Verification

Unveiling of Terahertz Emission from Ultrafast Demagnetization and the Anomalous Hall Effect in a Single Ferromagnetic Film

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Chinese Physics Letters 2024年第4期41卷 45-50页

作者：蓝志强李章顺徐浩然刘凡金钻明彭滟朱亦鸣 Terahertz Technology Innovation Research Institute Terahertz Spectrum and Imaging Technology Cooperative Innovation CenterShanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China

Using THz emission spectroscopy,we investigate the elementary spin dynamics in ferromagnetic single-layer Fe on a sub-picosecond *** demonstrate that THz radiation changes its polarity with reversal of the magnetization applied by the external magnetic *** addition,it is found that the sign of THz polarity excited from different sides is defined by the thickness of the Fe layer and Fe/dielectric *** on the thickness and symmetry dependences of THz emission,we experimentally distinguish between the two major contributions:ultrafast demagnetization and the anomalous Hall *** experimental results not only enrich understanding of THz electromagnetic generation induced by femtosecond laser pulses but also provide a practical way to access laser-induced ultrafast spin dynamics in magnetic structures.

关键词： magnetic magnetization polarity

In-situ construction of PDOL electrolyte with dual-reinforced stable interface for high-voltage lithium metal batteries

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Science China Chemistry 2024年第5期67卷 1664-1671页

作者： Yingkang Wu Yuzhou Bai Wujie Dong Xue Wang Wenqin Ma Fuqiang Huang State key lab of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050China

In-situ polymerized electrolytes significantly enhance the interfacial compatibility of lithium metal batteries(LMBs). Typically,in-situ polymerized 1,3-dioxolane(PDOL) exhibits low interfacial resistance, yet still suffers from low ionic conductivity and a narrow electrochemical stability window(ESW). Here, an ultra-stable PDOL-based polymer electrolyte is developed by incorporating plasticizers of tetramethylene sulfone(TMS) and fluorinated ethylene carbonate(FEC) into the 3D cross-linked network, achieving a significant enhancement in the transport capacity and efficiency of Li-ion. The ionic conductivity reaches3.63×10^(-4)S cm^(-1)even at room temperature, and the transference number(tLi^(+)) is even higher at 0.85. Furthermore, the ESW of this electrolyte can be increased to 4.5 V with the addition of TMS, which forms a thin and robust antioxidant cathode-electrolyte interface(CEI) on the surface of high-voltage LiCoO_(2). FEC generates an inorganic-rich solid-electrolyte interface(SEI) on the Li anode, which effectively inhibits the growth of lithium dendrites. Benefiting from the aforementioned advantages, the highvoltage lithium metal battery demonstrates outstanding long-cycle stability, with 93.2% capacity retention after 200 cycles. This work offers a straightforward and accessible method for the practical implementation of high energy density in-situ polymerized solid-state LMBs.

关键词： solid polymer electrolyte in-situ polymerization PDOL high-voltage LMBs

Data-driven casting defect prediction model for sand casting based on random forest classification algorithm

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China Foundry 2024年第2期21卷 137-146页

作者： Bang Guan Dong-hong Wang Da Shu Shou-qin Zhu Xiao-yuan Ji Bao-de Sun shanghai key lab of Advanced High-Temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State key lab of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China Hefei Casting and Forging Factory of Anhui Heli Co. LtdHefei 230000China State key laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan 430074China

The complex sand-casting process combined with the interactions between process parameters makes it difficult to control the casting quality,resulting in a high scrap rate.A strategy based on a data-driven model was proposed to reduce casting defects and improve production efficiency,which includes the random forest(RF)classification model,the feature importance analysis,and the process parameters optimization with Monte Carlo *** collected data includes four types of defects and corresponding process parameters were used to construct the RF *** results show a recall rate above 90% for all *** Gini Index was used to assess the importance of the process parameters in the formation of various defects in the RF ***,the classification model was applied to different production conditions for quality *** the case of process parameters optimization for gas porosity defects,this model serves as an experimental process in the Monte Carlo method to estimate a better temperature *** prediction model,when applied to the factory,greatly improved the efficiency of defect *** show that the scrap rate decreased from 10.16% to 6.68%.

关键词： sand casting process data-driven method classification model quality prediction feature importance

Highly selective and efficient photocatalytic NO removal:Charge carrier kinetics and interface molecular process

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Nano Research 2024年第3期17卷 1003-1026页

作者： Huan Shang Hongbao Jia Pengpeng Li Hao Li Wenbin Zhang Shuangjun Li Qing Wang Shuning Xiao Ding Wang Guisheng Li Dieqing Zhang School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China The Education Ministry key lab of Resource Chemistry Joint International Research Laboratory of Resource Chemistry of Ministry of EducationShanghai Key Laboratory of Rare Earth Functional Materialsand Shanghai Frontiers Science Center of Biomimetic CatalysisShanghai Normal UniversityShanghai 200234China School of Environmental Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The widespread nitrogen oxides(NOx,mainly in NO)in the atmosphere have threatened human health and ecological *** dilute NO(ppb)is difficult to efficiently remove via the traditional process due to its characteristics of low concentration,wide range,large total amount,*** can utilize solar energy to purify NO pollutants under mild conditions,but its application is limited due to the low selectivity of nitrate and poor activity of NO *** underlying reason is that the interface mechanism of NO oxidation is not clearly understood,which leads to the inability to accurately regulate the NO oxidation ***,the recent advances in the photocatalytic oxidation of NO are ***,the common strategies to effectively regulate carrier dynamics such as morphology control,facet engineering,defect engineering,plasma coupling,heterojunction and single-atom catalysts are ***,the progress of enhancing the adsorption and activation of reactants such as NO and O_(2) during NO oxidation is described in detail,and the corresponding NO oxidation mechanisms are ***,the challenges and prospects of photocatalytic NO oxidation are presented in term of nanotechnology for air pollution *** review can shed light on the interface mechanism of NO oxidation and provide illuminating information on designing novel catalysts for efficient NOx control.

关键词： nitrogen oxide(NO)oxidation photocatalysis NO/O_(2)activation charge carrier kinetics interfacial mechanism