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Foveated glasses-free 3D display with ultrawide field of view via a large-scale 2D-metagrating complex

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Light(Science & Applications) 2021年第11期10卷 2217-2225页

作者： Jianyu Hua Erkai Hua Fengbin Zhou Jiacheng Shi Chinhua Wang Huigao Duan Yueqiang Hu Wen Qiao Linsen Chen School of Optoelectronic Science and Engineering&Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University215006SuzhouChina Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province&Key Lab of Modern Optical Technologies of Education Ministry of China Soochow University215006SuzhouChina State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan University410082ChangshaChina SVG Optronics Co.Ltd215026SuzhouChina

Glasses-free three-dimensional(3D)displays are one of the game-changing technologies that will redefine the display industry in portable electronic ***,because of the limited resolution in state-of-the-art display panels,current 3D displays suffer from a critical trade-off among the spatial resolution,angular resolution,and viewing *** by the so-called spatially variant resolution imaging found in vertebrate eyes,we propose 3D display with spatially variant information *** experiences with smooth motion parallax are maintained at the central view,while the viewing angle is enlarged at the periphery *** is enabled by a large-scale 2D-metagrating complex to manipulate dot/linear/rectangular hybrid shaped ***,a video rate full-color 3D display with an unprecedented 160°horizontal viewing angle is *** thin and light form factors,the proposed 3D system can be integrated with off-the-shelf purchased flat panels,making it promising for applications in portable electronics.

关键词： portable spatially glasses

Effect of Early CO2 Curing and Subsequent Water Curing on the Interfacial Transition Zone between Cement Paste and Aggregates

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SSRN 2024年

作者： Huang, Yan Zhang, Jian Hu, Xiang Wang, Yue Drissi, Sarra Shi, Caijun College of Civil Engineering Hunan University Changsha410082 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province Changsha410082 China Key Laboratory of Building Safety and Energy Efficiency Ministry of Education Hunan University Changsha410082 China Department of Civil Engineering and Energy Technology Faculty of Technology Art and Design Oslo Metropolitan University PO box 4 St Olavs Plass OsloNO-0130 Norway

This study investigated the effect of early CO2 curing and subsequent saturated lime water curing on the interfacial transition zone (ITZ) between cement paste and aggregate, focusing on bond strength, pore structure, and phase compositions. The CO2 curing followed by water curing is an effective and sustainable method to enhance the ITZ's performance. The CO2 curing eliminated portlandite oriented within the ITZ and promoted the formation of calcite and silica-rich gels, resulting in a 10% reduction in porosity, a 20 µm decrease in thickness and a 50% enhancement in bond strength of the ITZ. The continuous hydration of the uncarbonated clinker during subsequent water curing further reduces the porosity and enhances the bond strength of the ITZ. Furthermore, the utilization of CO2 curing has demonstrated remarkable efficiency in enhancing the performance of the ITZ adjacent to limestone compared to granite. This can be attributed to the lower energy barrier for nucleation and faster rate of calcite nucleation on the surface of limestone. © 2024, The Authors. All rights reserved.

关键词： Carbon dioxide

Fatigue Crack Blunting Enabled by High Work Hardening in a High-Entropy Alloy at Intermediate Temperature

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SSRN 2024年

作者： Li, Weipeng Tan, Fusheng Li, Xuepan He, Binbin Jiang, Chao State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China China Academy of Safety Science and Technology Beijing100012 China Applied Mechanics Laboratory Department of Engineering Mechanics School of Aerospace Engineering Tsinghua University Beijing100084 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China

High-temperature fatigue service performances of metallic materials are very important for integrity of engineering structures. This study investigates the fatigue crack growth behavior and fatigue resistance of a CoCrFeNiMn high-entropy alloy (HEA) at an intermediate temperature of 673 K. High work hardening of HEA enabled fatigue crack blunting, leading to a unique sharpening–blunting–resharpening mechanism. Notably, it reduced the crack growth driving force and was responsible for the sudden decrease in fatigue crack growth rate. Many dislocations were further revealed to exist at the blunting crack tip. We believe that intense thermal activation instead of severe lattice distortion in the alloy results in sufficient dislocations at 673 K that facilitate crack growth relaxation and blunting. © 2024, The Authors. All rights reserved.

关键词： Entropy

A Finite Element Human Body Model of Chinese Midsize Male for Pedestrian safety Analysis

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SSRN 2024年

作者： Mo, Fuhao Liang, Ziyang Tian, Tengfei Li, Guibing Luo, Dian Xiao, Zhi Xiao, Sen State Key Laboratory of Advanced Design and Manufacture for Vehicle Hunan University Changsha410082 China Department of Orthopedics The Second Xiangya Hospital of Central South University Changsha410011 China Tianjin Key Laboratory of Power Transmission and Safety Technology for New Energy Vehicles Hebei University of Technology Tianjin300401 China School of Mechanical Engineering Hunan University of Science and Technology Xiangtan411201 China Hunan University of Science and Technology China

The most commonly used numerical human body models and anthropomorphic test devices (ATDs) in vehicle safety analysis are in the anthropometry of Western European or North American. However, the anthropometric differences between European/American and Chinese population are remarkable and have significant influences on pedestrian kinematics and injury response in vehicle crashes. Therefore, the current study aims to develop and validate a finite element (FE) human body model representing the anthropometry of Chinese 50th% adult male for pedestrian safety analysis and development of Chinese ATDs. Firstly, a human body pedestrian model, named as C-HBM (Chinese Human Body Model), was developed based on the medical image data of a volunteer selected according to both anthropometry and anatomy characteristics of 50th% Chinese adult male. Then, the biofidelity of the C-HBM pedestrian model was validated against cadaver impact test data reported in the literature at the segment and full-body level. Finally, the validated C-HBM pedestrian model was employed to predict Chinese pedestrian injuries in real world vehicle crashes. The results indicate that the C-HBM pedestrian model has a good capability in predicting human body mechanical response in cadaver tests and Chinese pedestrian leg and thorax injuries in real world vehicle crashes. Kinematic analysis shows that the C-HBM pedestrian model has less sliding on the hood surface, shorter movement in the horizontal direction, and higher pelvis displacement in the vertical direction than cadavers and the pedestrian model in the anthropometry of westerner due to anthropometric differences in the lower limbs. This implies that anthropometric differences between different ethnic groups should be considered in applications of numerical human body models and ATDs. The currently developed C-HBM pedestrian model provides a basic tool for vehicle safety design and evaluation in China market, and for development of Chinese ATDs. © 202

关键词： Pedestrian safety

Numerical Study on the Performance, Combustion Characteristics, and Energy Flow Distribution of Gasoline-Powered vehicle Under Synthetic Actual Driving Test Cycle

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SSRN 2023年

作者： Qiao, Junhao Liu, Jingping Jia, Dongdong Fu, Jianqin Liu, Shenghui Li, Yangyang Guan, Jinhuan Wang, Shuqian State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha410082 China College of Biological and Chemical Engineering Zhejiang University of Science and Technology Hangzhou310023 China State Key Laboratory of Automotive Safety and Energy Tsinghua University Beijing100084 China Hunan University China

In order to meet the requirements of vehicle performance prediction and optimization, a synthetic actual driving test cycle (ADTC) is proposed to accurately predict the related performance, and energy distribution characteristics of vehicles with urban road conditions. Meanwhile, a multi-physical field vehicle energy management simulation model is built and has been carefully verified. Thus, the relevant characteristic parameters of the vehicle under the ADTC are numerically analyzed, and the interfering factors of energy items are revealed and compared. The results show that the synthetic ADTC can more accurately reflect the vehicle's operating conditions and provide guidance for more detailed vehicle optimization. The BTE of the engine under ADTC varies in the range of 14.88 % to 30.54 %, that is lower than WLTC and NEDC. Besides, the proportion of combustion loss is WLTC, ATDC and NEDC from the largest to the smallest, which is mainly related to the complexity of speed variation. In particular, the ratio of exhaust loss and combustion heat loss to total energy is very large under any test cycle. The purpose of this study is to achieve real-time control of vehicle performance under transient conditions and achieve the goal of emission reduction energy utilization optimization. © 2023, The Authors. All rights reserved.

关键词： vehicle performance

Nucleophilic cleavage of C-F bonds by Brùnsted base for rapid synthesis of fluorophosphate materials

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National Science Review 2025年第03期 292-303页

作者： Qingfeng Fu Zihao Chang Peng Gao Wang Zhou Hongliang Dong Peifeng Huang Aiping Hu Changling Fan Peitao Xiao Yufang Chen Jilei Liu College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology Hunan University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Center for High Pressure Science and Technology Advanced Research State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences College of Aerospace Science and Engineering National University of Defense Technology

Fluorochemicals are a rapidly expanding class of materials used in a variety of fields including pharmaceuticals, metallurgy, agrochemicals, refrigerants, and in particular, alkali metal ion ***, achieving one-step synthesis of pure fluorophosphate compounds in a well-controlled manner remains a formidable challenge due to the volatilization of fluorine during the heat treatment process. One feasible method is to cleave the C–F bond in polytetrafluoroethylene（PTFE） during synthesis to create a fluorine-rich atmosphere and strongly reducing environment. However, the inert nature of the C–F bond in PTFE presents a significant obstacle, as it is the strongest single bond in organic compounds. To address this predicament, we propose a fluorine-compensating strategy that involves cleavage of the C–F bonds by nucleophilic SN2-type reactions of Br?nsted base（ammonia） enabling fluorine compensation. The decomposed products（NH2· and C·） also result in the formation of micropores（via NH3escape） and in-situ carbon coating（via C· polymerization）. The resultant cathode delivers a superior potassium storage capability including high rate performance and capacity retention. This contribution not only overcomes the obstacles associated with the inert C–F bond in fluororesin, but also represents a significant step forward in the development of fluorine-containing compounds.

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Sulfur Doped Hollow Carbon Nanofiber Anodes for Fast-Charging Potassium-Ion Storage

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SSRN 2022年

作者： Wang, Fei Li, Du Zhang, Guanhua Li, Jingyuan Zhang, Chengzhi Wei, Donghai Yang, Jianxiao Ye, Chong Tan, Jun Liu, Jinshui State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology College of Materials Science and Engineering Hunan University Changsha410082 China Ji Hua Laboratory Guangdong Foshan528000 China

Sulfur doping can bridge durable active sites, induce C-S electron coupling to produce unparalleled Faraday conversion, break the limitations of ion storage capacitance, and therefore is an effective way to design carbon materials with improved electrochemical performance. However, sulfur doping mechanism, especially how to design S-rich by atomic transition among carbon membered-ring structure of anodes remains a confusing topic. Herein, the linear relationship between sulfur and nitrogen content is found, and the tendency of sulfur to replace pyrrolic nitrogen is demonstrated. The sulfur replaces part of nitrogen atoms and form C-S bonds with binds covalently to carbon skeleton, where S-rich hollow carbon nanofibers (NHCFs-S) are synthesized. The introduction of high S-doping in carbon results to the improvement of conductivity, Faraday reaction activity and pseudocapacitive adsorption behavior. For potassium-ion batteries, the fabricated NHCFs-S material delivers a 369 mAh g−1 high capacity at 1.0 A g−1 after 100 cycles with 80% initial coulombic efficiency and a desirable rate capability of 261 mAh g−1 even at 5.0 A g−1. This work provides a selection for high-performance anodes design and a reference for the future research of high sulfur doped in carbon materials. © 2022, The Authors. All rights reserved.

关键词： Sulfur

Superfolded configuration induced low thermal conductivity in two-dimensional carbon allotropes revealed via machine learning force constant potential

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arXiv

arXiv 2023年

作者： Yu, Linfeng Dong, Kexin Yang, Qi Zhang, Yi Zheng, Xiong Wang, Huimin Qin, Zhenzhen Qin, Guangzhao National Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China School of Physics and Microelectronics Zhengzhou University Zhengzhou450001 China Research Institute of Hunan University in Chongqing Chongqing401133 China Greater Bay Area Institute for Innovation Hunan University Guangdong Province Guangzhou511300 China

Understanding the fundamental link between structure and functionalization is crucial for the design and optimization of functional materials, since different structural configurations could trigger materials to demonstrate diverse physical, chemical, and electronic properties. However, the correlation between crystal structure and thermal conductivity (κ) remains enigmatic. In this study, taking two-dimensional (2D) carbon allotropes as study cases, we utilize phonon Boltzmann transport equation (BTE) along with machine learning force constant potential to thoroughly explore the complex folding structure of pure sp2 hybridized carbon materials from the perspective of crystal structure, mode-level phonon resolved thermal transport, and atomic interactions, with the goal of identifying the underlying relationship between 2D geometry and κ. We propose two potential structure evolution mechanisms for targeted thermal transport properties: in-plane and out-of-plane folding evolutions, which are generally applicable to 2D carbon allotropes. It is revealed that the folded structure produces strong symmetry breaking, and simultaneously produces exceptionally strongly suppressed phonon group velocities, strong phonon-phonon scattering, and weak phonon hydrodynamics, which ultimately lead to low κ. The insight into the folded effect of atomic structures on thermal transport deepens our understanding of the relationship between structure and functionalization, which offers straightforward guidance for designing novel nanomaterials with targeted κ, as well as propel developments in materials science and engineering. Copyright © 2023, The Authors. All rights reserved.

关键词： Phonons

Revealing the roles of martensitic transformation in affecting the fatigue resistance of austenitic stainless steel with heterogeneous grain size distribution

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Scripta Materialia 2024年 246卷

作者： Li, W.P. He, B.B. Sun, Y.H. Yen, H.W. Huang, M.X. Jiang, C. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China China Academy of Safety Science and Technology Beijing100012 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China Department of Materials Science and Engineering National Taiwan University Taipei10617 Taiwan High Entropy Materials Center National Tsing Hua University Hsinchu30013 Taiwan Department of Mechanical Engineering The University of Hong Kong Hong Kong Hong Kong

The present work investigates the roles of martensitic transformation on the small fatigue crack growth behavior and fatigue resistance of a 316 L austenitic stainless steel. Martensitic transformation with varied block size takes place along crack path and at the crack tip. The large martensite blocks are vulnerable to crack propagation as the cracks can easily penetrate the block interior, leaving flat facets on the fracture surface. In contrast, the ultrafine martensite blocks can provide an enduring resistance on fatigue crack extension and deflect the crack propagation by cracking along their irregular and dense block boundaries. Considering the correlation between martensite block size, mechanical stability and prior austenite grain size, the present work suggests that austenite grain refinement is beneficial for improving fatigue properties of steels containing metastable austenite grains. © 2024

关键词： Martensitic transformations