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Topological dependence of mechanical responses of solidification microstructures in aluminum brazed joints

中国有色金属学会会刊：英文版 2003年第6期13卷 1296-1300页

作者：高峰钱乙余 D.P.Sekulic 马鑫 F.Yoshida State Key Laboratory of Advanced Production Technology Center for Robotics and Manufacturing Systems Department of Mechanical System Engineering

The main objective is to provide an evidence of spatial dependence of mechanical responses of a heterogeneous aluminum brazed joint re-solidified clad, and to confirm a sufficient sensitivity of a nano-indentation—load curve method for identifying the dependence. Topological features of a network of solidification microstructures(α phase and eutectic), formed during quench in a brazing process of aluminum alloy, influence significantly dynamic mechanical responses of resulting heterogeneous material. Nano/micro indentation depth vs load characteristics of differing phases suggest a spatially sensitive mechanical response of a re-solidified fillet in the joint zone. Hence, a spatial distribution, pattern formations and other morphological characteristics of microstructures have a direct impact on an ultimate joint integrity. Topology-induced variations of indentation—load curves was presented. A hypothesis involving microstructures’ spatial distribution vs mechanical response was formulated.

关键词：铝铜焊显微结构凝固拓扑相关机械响应焊接铝合金

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VideoQA-SC: Adaptive Semantic Communication for Video Question Answering

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IEEE Journal on Selected Areas in Communications 2025年

作者： Guo, Jiangyuan Chen, Wei Sun, Yuxuan Xu, Jialong Ai, Bo State Key Laboratory of Advanced Rail Autonomous Operation China Beijing Jiaotong University School of Electronic and Information Engineering Beijing China School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China Beijing Jiaotong University Frontiers Science Center for Smart High-speed Railway System School of Electronic and Information Engineering Beijing China Zhengzhou University School of Information Engineering Zhengzhou China

Although semantic communication (SC) has shown its potential in efficiently transmitting multimodal data such as texts, speeches and images, SC for videos has focused primarily on pixel-level reconstruction. However, these SC systems may be suboptimal for downstream intelligent tasks. Moreover, SC systems without pixel-level video reconstruction present advantages by achieving higher bandwidth efficiency and real-time performance of various intelligent tasks. The difficulty in such system design lies in the extraction of task-related compact semantic representations and their accurate delivery over noisy channels. In this paper, we propose an end-to-end SC system, named VideoQA-SC for video question answering (VideoQA) tasks. Our goal is to accomplish VideoQA tasks directly based on video semantics over noisy or fading wireless channels, bypassing the need for video reconstruction at the receiver. To this end, we develop a spatiotemporal semantic encoder for effective video semantic extraction, and a learning-based bandwidth-adaptive deep joint source-channel coding (DJSCC) scheme for efficient and robust video semantic transmission. Experiments demonstrate that VideoQA-SC outperforms traditional and advanced DJSCC-based SC systems that rely on video reconstruction at the receiver under a wide range of channel conditions and bandwidth constraints. In particular, when the signal-to-noise ratio is low, VideoQA-SC can improve the answer accuracy by 5.17% while saving almost 99.5% of the bandwidth at the same time, compared with the advanced DJSCC-based SC system. Our results show the great potential of SC system design for video applications. © 1983-2012 IEEE.

关键词： Bandwidth

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Functionally graded composite ceramics: design, manufacturing, properties and applications

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Progress in Materials Science 2025年 154卷

作者： Zheng, Yingqi Sun, Jialin Li, Xiao Zhao, Jun Wang, Haibin Yun, Xialun Li, Zhuan Huang, Zhifu School of Mechanical Electrical & Information Engineering Shandong University Weihai264209 China Shenzhen Research Institute of Shandong University Shenzhen518057 China State Key Laboratory for Powder Metallurgy Central South University Changsha410083 China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou730000 China Weihai Weiying Tool Co. Ltd. Weihai264210 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of MOE School of Mechanical Engineering Shandong University Jinan250061 China College of Materials Science and Engineering Key Laboratory of Advanced Functional Materials Education Ministry of China Beijing University of Technology Beijing100124 China State Key Laboratory for Manufacturing System Engineering School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an710049 China

Functionally graded ceramics (FGCs) are a class of advanced ceramic materials with spatially varying composition, phase or microstructure, designed to achieve continuous or discrete variations in material properties through advanced techniques. They have played a crucial role in replacing conventional ceramic materials in advanced applications as a function of its superior performance in balancing mutually exclusive properties (toughness and strength etc.). Herein, we apply towards comprehensively discuss the emerging advancements in FGCs, highlighting their design, manufacturing, properties and applications. Different design principles were discussed from structural design, stress design, composition design to computer-aided design. Furthermore, in-depth perspective analysis of advanced processing technologies was summarized including powder metallurgy, slip casting, and additive manufacturing. Additionally, the thermal and mechanical properties of FGCs were summarized, accompanied by the corresponding property enhancement mechanisms. Finally, the critical challenges and potential applications in further developing functionally graded ceramics were provided. This comprehensive overview of FGC would be referenceable and helpful to the researchers working in this area or new-come to this field, thereby identifying the research gaps for advancing the field. © 2025 Elsevier Ltd

关键词： Porcelain

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Type Synthesis of Two-Degrees-of-Freedom Rotational Parallel Mechanism with Two Continuous Rotational Axes

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 694-702页

作者： XU Yundou ZHANG Dongsheng WANG Min YAO Jiantao ZHAO Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of National Education Yanshan University Library Yanshan University

The two-rotational-degrees-of-freedom（2R） parallel mechanism（PM） with two continuous rotational axes（CRAs） has a simple kinematic *** is therefore easy to implement trajectory planning,parameter calibration,and motion control,which allows for a variety of application ***,no systematic analysis on structural constraints of the 2R-PM with two CRAs has been performed,and there are only a few types of 2R-PM with two ***,a theory regarding the type synthesis of the 2R-PM with two CRAs is systematically ***,combining the theories of reciprocal screw and space geometry,the spatial arrangement relationships of the constraint forces applied to the moving platform by the branches are explored,which give the 2R-PM two *** different distributions of the constraint forces in each branch are also *** the basis of the obtained structural constraints of branches,and considering the geometric relationships of constraint forces in each branch,the appropriate kinematic chains are *** the reasonable configuration of branch kinematic chains corresponding to every structural constraint,a series of new 2R-PMs with two CRAs are finally obtained.

关键词： type synthesis continuous rotational axes two rotational degrees of freedom parallel mechanism constraint force

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Sidelink Evolution Toward Enhanced Data Rate: Experimental and Simulation Validation

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IEEE Transactions on Vehicular Technology 2025年

作者： Kim, Junhyeong Wang, Yiran Yan, Dong Guan, Ke Chung, Heesang Electronics and Telecommunications Research Institute 6G Wireless Access System Research Section Daejeon34129 Korea Republic of Beijing Jiaotong University School of Electronic and Information Engineering Beijing100044 China Beijing Jiaotong University State Key Laboratory of Advanced Rail Autonomous Operation Beijing100044 China

This paper investigates the feasibility of millimeter-wave (mmWave) sidelink (SL) communication in typical urban road scenarios. Initially, recent research and standardization progress on vehicle-to-everything (V2X) communication, with a focus on its operation in mmWave bands, are reviewed. Subsequently, the design and deployment of a mmWave V2X testbed are described, along with experimental evaluation results showcasing its real-world performance. Additionally, the impact of beam management in mmWave SL communication is explored through ray-tracing simulations in a distinct urban road scenario, underscoring its significance. Through both experimental and simulation evaluations, we demonstrate the suitability of mmWave SL for supporting enhanced V2X applications and offer valuable insights into designing beam management for mmWave SL communication in typical urban road environments. © 1967-2012 IEEE.

关键词： Highway administration

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2D cotton fabric coated with 3D chitosan/carbon-black aerogel for continuous efficient solar desalination

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Chemical Engineering Journal 2025年 514卷

作者： Ren, Huihui Hu, Jinjing Pazuki, Mohammad-Mahdi Peng, Ye Maleki, Farhad Salimi, Mohsen Asban, MohammadAmin Amidpour, Majid Ma, Zaifei Li, Haoxuan Chen, Zhigang State Key Laboratory of Advanced Fiber Materials College of Materials Science and Engineering Donghua University Shanghai201620 China Department of Energy System Engineering Faculty of Mechanical Engineering K.N. Toosi University of Technology Tehran Iraq Renewable Energy Research Department Niroo Research Institute Tehran Iraq Center for Advanced Low-dimension Materials Donghua University Shanghai201620 China

Solar-driven seawater desalination has garnered considerable attention in the past ten years. Two-dimensional (2D) membranes exhibit remarkable flexibility but are limited by unsatisfactory surface area and photoabsorption. Three-dimensional (3D) photothermal materials possess large evaporation areas and hydrophilic frameworks but suffer from inflexibility and inefficient water-transfer. To leverage their advantages while circumventing their limitations, we present a fabric-interleaved-aerogel (FIA) which is prepared by coating 3D chitosan/carbon-black (CSCB) aerogel on 2D cotton fabric. FIA exhibits an impressive solar absorption efficiency of 96.78%, which is attributed to the multilayered structure of the 3D aerogel. Furthermore, FIA exhibits good flexibility and efficient water-transfer capacity due to the 2D fabric substrate. Importantly, FIA can be adeptly configured as a hanging evaporator with simulated seawater, achieving an exceptional evaporation rate of 2.67 kg m−2 h−1 under 1 sun irradiation. The hanging FIA not only surpasses that of traditional 2D evaporators but also matches the performance of 3D evaporators, effectively addressing the challenge of salt separation associated with 3D systems. This study provides significant insights into the design of efficient photothermal materials, specifically targeting scalable solar-powered seawater desalination. © 2025 Elsevier B.V.

关键词： Desalination

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Diffusion-Based Model for Parametric Ki Generation From Total-Body Dynamic PET of Short-Duration Scan

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IEEE Transactions on Radiation and Plasma Medical Sciences 2025年

作者： Wen, Meiyuan Wu, Yaping Huang, Zhenxing He, Xiangjian Tesema, Fiseha B. Chen, Zixiang Gao, Yunlong Li, Wenbo Yang, Xinlan Yang, Yongfeng Zheng, Hairong Liang, Dong Wang, Meiyun Hu, Zhanli Chinese Academy of Sciences Research Center for Medical AI Shenzhen Institute of Advanced Technology China State Key Laboratory of Biomedical Imaging Science and System Key Laboratory of Biomedical Imaging Science and System Chinese Academy of Sciences China University of Nottingham Ningbo China School of Computer Science Ningbo315104 China Henan Provincial People's Hospital People's Hospital of Zhengzhou University Department of Medical Imaging Zhengzhou450003 China United Imaging Healthcare Group Central Research Institute Shanghai201807 China

Dynamic positron emission tomography (PET) parametric imaging typically requires a 60-minute acquisition period, causing patient discomfort and reducing clinical efficiency. This study explores the feasibility of generating parametric Ki images from 10-minute dynamic PET images acquired in the early or late scanning phases employing a multi-channel feature fusion cold sampling (MCFFCoS) framework. PET data from 103 patients are acquired using the uEXPLORER total-body PET/CT scanner during 60-minute scans. This study conducts deep learning experiments, taking early-phase or late-phase PET images as input, respectively. The generated Ki images are evaluated by visual quality and quantitative metrics, including root mean squared error (RMSE), structural similarity index (SSIM), and peak signal-to-noise ratio (PSNR). Volumes of interest (VOIs) analysis is performed using linear regression and Bland-Altman plots. In the quantitative evaluation of total-body data, the parametric Ki images generated from late-phase PET data generally outperform those derived from early-phase data. The analysis of VOIs indicates that the appropriate scanning protocol for PET parametric imaging may vary for different body regions. The deep learning approach is able to generate high-quality parametric Ki images from 10-minute dynamic PET scans, bypassing the requirements of long acquisition time for the estimation of blood input function in kinetic modeling. © 2017 IEEE.

关键词： Positron emission tomography

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Study on the High-Speed Penetration and Shear Failure Mechanism of Beach Sand

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Materials 2025年第9期18卷 1922-1922页

作者： Zhu, Jianzhong Li, Jiangquan Kong, Yun Dong, Mingming Li, Yuqiong Zou, Meng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Key Laboratory for Bionics Engineering of Education Ministry Jilin University Changchun130022 China School of Mechanical Engineering Beijing Institute of Technology Beijing100081 China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing100190 China Guangdong Aerospace Research Academy Nansha Guangzhou511458 China

In this paper, the contact parameters of beach sand are calibrated based on the discrete element method and the optimal design method, and the obtained parameters by calibration are used as input for the angle of repose simulation. The relative error between angle of repose simulation results and experimental results is 3.27%. Based on the penetration and shear tests, simulation models were constructed to study the pressure shear failure mechanism of beach sand under high-speed conditions. The high-speed penetration simulation shows that with the increase of the penetration rate, the influence area of the sinkage plate gradually increases, and the stress of sand particles also increases. When the penetration rate increased from 0.5 m/s to 8 m/s, the pressure on the plate increased 12.7 times, indicating that the bearing capacity of the sand increased significantly with the increase of the penetration rate. The high-speed shear simulation shows that in the stable shear stage, the average shear torque initially increases slightly with the increase of speed, and then decreases significantly when the speed exceeds 4 m/s. This is because as the shear rate increases, the disturbance of the soil by the shear plate increases, the velocity of soil particles increases, resulting in a decrease in the number of soil particles in contact with the shear plate, thereby reducing the shear torque. © 2025 by the authors.

关键词： Fracture mechanics

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A CVAE-based generative model for generalized B₁ inhomogeneity corrected chemical exchange saturation transfer MRI at 5 T

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NeuroImage 2025年 312卷 121202-121202页

作者： Zhang, Ruifen Zhang, Qiyang Wu, Yin Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institute of Advanced Technology Chinese Academy of Sciences 1068 Xueyuan Boulevard Xili Nanshan Guangdong Shenzhen 518055 China Research Center for Medical AI Shenzhen Institute of Advanced Technology Chinese Academy of Sciences 1068 Xueyuan Boulevard Xili Nanshan Guangdong Shenzhen 518055 China Key Laboratory of Biomedical Imaging Science and System Chinese Academy of Sciences 1068 Xueyuan Boulevard Xili Nanshan Guangdong Shenzhen 518055 China State Key Laboratory of Biomedical Imaging Science and System 1068 Xueyuan Boulevard Xili Nanshan Guangdong Shenzhen 518055 China

Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has emerged as a powerful tool to image endogenous or exogenous macromolecules. CEST contrast highly depends on radiofrequency irradiation B₁ level. Spatial inhomogeneity of B₁ field would bias CEST measurement. Conventional interpolation-based B₁ correction method required CEST dataset acquisition under multiple B₁ levels, substantially prolonging scan time. The recently proposed supervised deep learning approach reconstructed B₁ inhomogeneity corrected CEST effect at the identical B₁ as of the training data, hindering its generalization to other B₁ levels. In this study, we proposed a Conditional Variational Autoencoder (CVAE)-based generative model to generate B₁ inhomogeneity corrected Z spectra from single CEST acquisition. The model was trained from pixel-wise source–target paired Z spectra under multiple B₁ with target B₁ as a conditional variable. Numerical simulation and healthy human brain imaging at 5 T were respectively performed to evaluate the performance of proposed model in B₁ inhomogeneity corrected CEST MRI. Results showed that the generated B₁-corrected Z spectra agreed well with the reference averaged from regions with subtle B₁ inhomogeneity. Moreover, the performance of the proposed model in correcting B₁ inhomogeneity in APT CEST effect, as measured by both MTR_asym and MTR_R at 3.5 ppm, were superior over conventional Z/contrast-B₁-interpolation and other deep learning methods, especially when target B₁ were not included in sampling or training dataset. In summary, the proposed model allows generalized B₁ inhomogeneity correction, benefiting quantitative CEST MRI in clinical routines. © 2025 The Authors

关键词： B1 inhomogeneity Chemical exchange saturation transfer (CEST) Conditional variational autoencoder (CVAE)

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TTOP model simulation of long-term (1981–2100) permafrost dynamics of the Tibetan Plateau

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Geoderma 2025年 457卷

作者： Zhao, Yufeng Yao, Yingying Jin, Huijun Li, Xin Cao, Bin Ran, Youhua Kuang, Xingxing Zheng, Chunmiao Institute of Global Environmental Change Xi'an Jiaotong University Xi'an710049 China School of Ecology China-Russia Joint Laboratory of Cold Regions Engineering and Environment Permafrost Institute Northeast Forestry University Harbin 150040 China State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou730000 China State Key Laboratory of Tibetan Plateau Earth System Environment and Resources National Tibetan Plateau Data Center Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China Heihe Remote Sensing Experimental Research Station State Key Laboratory of Cryospheric Science and Frozen Soil Engineering Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000 China School of Environmental Science and Engineering Southern University of Science and Technology Shenzhen518055 China Eastern Institute for Advanced Study Eastern Institute of Technology Ningbo315200 China

The Tibetan Plateau (TP) covers the largest regions under low- and mid-latitude permafrost. The evolution of permafrost has significantly affected the hydrology, biogeochemistry, and infrastructure of Asia. However, model reconstructions of long-term permafrost evolution with high accuracy and reliability are insufficient. Here, spatial changes in mean annual ground temperature at the depth where the annual amplitude is zero (MAGT) on the TP since 1981 were modeled and validated based on temperature records from 155 boreholes, and future changes were predicted under scenarios from the Climate Model Intercomparison Project 6 (CMIP6). The results indicated that the MAGT on the TP was approximately 1.5 °C (2010 – 2018), and the corresponding permafrost extent on the TP is estimated to be approximately 1.03 × 106 km2, which is projected to decrease to 0.77 × 106, 0.50 × 106, 0.30 × 106, and 0.17 × 106 km2 under the scenarios of shared socioeconomic pathway (SSP)126, SSP245, SSP370, and SSP585, respectively, by 2100. As predicted in the SSP585 scenario, permafrost is predicted to largely disappear from many basins of major Asian rivers, such as the Yarlung Zangpo-Brahmaputra, Nu-Salween, and Lancang-Mekong Rivers, between 2041 and 2060, followed by the Yellow and Yangtze Rivers between 2061 and 2080. Moreover, the original stable permafrost in the West Kunlun Mountains will change to transitional and unstable conditions. Our study offers comprehensive datasets of year-to-year ground temperatures and permafrost extent maps for the TP, which can serve as a fundamental resource for further investigations on the hydrogeology, engineering geology, ecology, and geochemistry of the TP. © 2025 The Author(s)

关键词： Permafrost

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