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A grain level model for deformation and failure of ultrafine-grained tungsten

science China(Technological sciences) 2019年第5期62卷 755-761页

作者： REN Ke CHEN LiRong CHENG YangYang WANG JianXiang DUAN HuiLing State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science College of EngineeringPeking University Key Laboratory of High Energy Density Physics Simulation Center of Applied Physics and Technology BIC-ESAT and IFSA Collaborative Innovation Center of MoE Peking University

Ultrafine-grained tungsten(UFG W) produced by severe plastic deformation technology has many potential applications due to its high strength and ductility. To reveal the mechanism for the high ductility of UFG W, the deformation and failure behaviors of coarse-grained tungsten(CG W) and UFG W have been compared based on a three-dimensional crystal plastic finite element method(CPFEM) simulation. Cohesive element method has been utilized to model the behavior of grain boundaries(GBs). Both plastic deformation in grain interiors and grain boundary opening have been observed in different periods of deformation in UFG W. It is concluded that the high GB density and elongated microstructure in the UFG W suppress crack propagation, decrease the stress concentration and impurity concentration on GBs, therefore enhance the ductility of the material.

关键词： ultrafine grain(UFG) tungsten crystal plasticity interface failure

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S$^{\text{4}}$TP: Social-Suitable and Safety-Sensitive Trajectory Planning for Autonomous Vehicles

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent Vehicles 2023年第2期9卷 3220-3231页

作者： Xiao Wang Ke Tang Xingyuan Dai Jintao Xu Quancheng Du Rui Ai Yuxiao Wang Weihao Gu Engineering Research Center of Autonomous Unmanned System Technology Ministry of Education Anhui University Hefei China Haomo Technology Company Ltd. Beijing China State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China Qingdao Academy of Intelligent Industries Qingdao China School of Computer and Communication Engineering University of Science and Technology Beijing Beijing China School of Artificial Intelligence University of Chinese Academy of Sciences Beijing China

In public roads, autonomous vehicles (AVs) face the challenge of frequent interactions with human-driven vehicles (HDVs), which render uncertain driving behavior due to varying social characteristics among humans. To effectively assess the risks prevailing in the vicinity of AVs in social interactive traffic scenarios and achieve safe autonomous driving, this article proposes a social-suitable and safety-sensitive trajectory planning (S $^{\text{4}}$ TP) framework. Specifically, S $^{\text{4}}$ TP integrates the Social-Aware Trajectory Prediction (SATP) and Social-Aware Driving Risk Field (SADRF) modules. SATP utilizes Transformers to effectively encode the driving scene and incorporates an AV's planned trajectory during the prediction decoding process. SADRF assesses the expected surrounding risk degrees during AVs-HDVs interactions, each with different social characteristics, visualized as two-dimensional heat maps centered on the AV. SADRF models the driving intentions of the surrounding HDVs and predicts trajectories based on the representation of vehicular interactions. S $^{\text{4}}$ TP employs an optimization-based approach for motion planning, utilizing the predicted HDVs' trajectories as input. With the integration of SADRF, S $^{\text{4}}$ TP executes real-time online optimization of the planned trajectory of AV within low-risk regions, thus improving the safety and the interpretability of the planned trajectory. We have conducted comprehensive tests of the proposed method using the SMARTS simulator. Experimental results in complex social scenarios, such as unprotected left-turn intersections, merging, cruising, and overtaking, validate the superiority of our proposed S $^{\text{4}}$ TP in terms of safety and rationality. S $^{\text{4}}$ TP achieves a pass rate of 100% across all scenarios, surpassing the current state-of-the-art methods Fanta of 98.25% and Predictive-Decision of 94.75%.

关键词： Trajectory Safety Vehicles Trajectory planning Autonomous vehicles Risk management Behavioral sciences

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Correspondence Principle, Ergodicity, and Finite-Time Dynamics

引用

Physical Review Letters 2025年第13期134卷 130402-130402页

作者： Zhen-Qi Chen Rui-Hua Ni Yalei Song Liang Huang Jiao Wang Giulio Casati Lanzhou Center for Theoretical Physics Lanzhou University Lanzhou 730000 Gansu China Key Laboratory of Theoretical Physics of Gansu Province Key Laboratory for Quantum Theory and Applications of MOE and School of Physical Science and Technology Lanzhou University Lanzhou 730000 Gansu China Department of Physics Xiamen University Xiamen 361005 Fujian China Center for Nonlinear and Complex Systems Dipartimento di Scienza e Alta Tecnologia Università degli Studi dell’Insubria via Valleggio 11 22100 Como Italy

The quantum-classical correspondence stands out as one of the most intriguing challenges in the realm of quantum mechanics. Within the context of quantum chaos, the conventional approach, which relies on spectral statistics to infer distinct classical dynamical properties, fails in typical scenarios, such as slow relaxation processes, dynamical localization, or other deviations from ergodicity. To address this difficulty, we propose a novel approach, the essence of which lies in associating a quantum energy shell with classical finite-time trajectories. Our results extend the knowledge of quantum-classical correspondence, offer explanations for previously conflicting findings, and also bear significance for applications in quantum metrology, sensing, and computation when the determination of the ergodicity degree of the quantum states is in need.

关键词： Quantum chaos

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Stable wide-temperature and low volume expansion Al batteries:Integrating few-layer graphene with multifunctional cobalt boride nanocluster as positive electrode

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Nano Research 2020年第2期13卷 419-429页

作者： Li-Li Chen Na Li Huifeng Shi Yuefei Zhang Wei-Li Song Shuqiang Jiao Haosen Chen Daining Fang Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081China School of Materials Science&Engineering Beijing Institute of TechnologBeijing 100081China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Institute of Microstructure and Property of Advarced Materials Beijing University of TechnologyBejing 100124China State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking UniversityBeijing 100871China

To achieve stable positive electrode for promoting the overall electrochemical performance of Al batteries(ABs),here novel cobalt boride(CoB)nanoclusters are synthesized to construct composite electrodes with few-layer graphene(FLG).Due to the presence of amorphous channels in the employed CoB nanoclusters,the ABs with FLG/CoB composite positive electrodes exhibit high *** and both mechanical and electrochemical stability in the *** assistance of in situ scanning electron microscopy(SEM),the observation results suggest that the positive electrode of CoB nanoclusters holds almost ignorable volume variation upon electrochemical processes,which substantially alleviates the massive electrode expansion induced by the anion intercalation in the composite positive ***,the composite positive electrodes provide stable reversible energy storage capability within a broadened temperature range(-30-60℃),promising a novel strategy to design advanced ABs positive electrodes with enhanced overall energy storage performance.

关键词： Al batteries positive electrode cobalt boride nanoclusters ionic liquid broad temperature

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Key Techniques on Unified Identity Authentication in OpenMBEE Integration

Key Techniques on Unified Identity Authentication in OpenMBE...

引用

IEEE International Conference on Electronics and Communication Engineering (ICECE)

作者： Junjie Xue Junhua Zhou Guoqiang Shi Chaoqun Feng Penghua Liu Hongyan Quan Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation Center Beijing China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing China Beijing Simulation Center Science and Technology on Space System Simulation Laboratory Beijing China School of Computer Science and Technology East China Normal University Shanghai China

ISBN: (纸本)9781728188577

In order to make full use of the concept of model-based systems engineering (MBSE) and the collaborative design capability of the open model-based engineering environment (OpenMBEE) in establishing complex product development platform, we propose an effective method to solve the problem of unified identity authentication in OpenMBEE integration. The proposed method is based on the Model View Controller(MVC) architecture in OpenMBEE, which has the characteristics strong plasticity and can be benefit for expanding the function in the controller layer. In our research, we make full use of the Software Development Kit (SDK) of OpenMBEE to expand the existing functions in the controller layer, and increase the function of communicating with the application development platform, then realize the function of sharing user authentication information between the development platform and OpenMBEE. After expansion, the system includes three modules, including the Front-end Service Module(FSM), MQ based Information Receiving Service Module(IFRSM), and the OpenMBEE Backend Server Module(BSM). The effectiveness of the proposed strategies is verified by some practical instances, which verifies that our study can provide an effective design idea for the identity authentication in OpenMBEE integration.

关键词： Analytical models Databases Authentication Computer architecture Control systems Data models Software

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Impact of Ligand Fields on Kubas Interaction of Open Copper Sites in Mofs with Hydrogen Molecules: An Electronic Structural Insight

SSRN

引用

SSRN 2024年

作者： Nguyen-Thuy, Trang Tran-Van, Hoan Nguyen-Hoang, Linh Nguyen-Minh, Hoang Phan, Bach Thang Nguyen-The, Toan Kawazoe, Yoshiyuki Faculty of physics University of Science Vietnam National University – Hanoi Hanoi Viet Nam School of engineering physics Hanoi University of Technology Hanoi Viet Nam Center for Innovative Materials and Architectures Vietnam National University Ho Chi Minh City Ho Chi Minh City Viet Nam Vietnam National University HoChiMinh City Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems University of Science Vietnam National University – Hanoi Hanoi Viet Nam New Industry Creation Hatchery Center Tohoku University Sendai980-8579 Japan Department of Physics and Nanotechnology SRM Institute of Science and Technology Tamil Nadu Kattankulathur603203 India School of Physics Institute of Science Suranaree University of Technology 111 University Avenue Nakhon Ratchasima30000 Thailand

Using DFT calculations, we investigate hydrogen sorption on open copper sites in various ligand coordinations of metal-organic frameworks (MOFs), including the triangle coordination T(CuL3) in MFU-4l, the linear coordination L(CuL2) in NU2100 and the paddlewheel coordination P(CuL4)2 in HKUST-1. By examining the ligand field splitting of d states and spd hybridizations in copper, we reveal the electronic mechanisms influencing hydrogen sorption performance. Despite Cu+ oxidization state which is expected to facilitate strong Kubas interaction with hydrogen molecules, the vacant s-p-dz2 hybrid orbitals of the open copper site in the L(CuL2) coordination are unsuitable for overlapping with the H2 s bonding orbital, preventing hydrogen adsorption. In contrast, the T(CuL3) and P(CuL4)2 coordinations enable hydrogen adsorption by inducing suitable hydrid orbitals. The vacant Cu s-p-dz2 hybrid orbitals in these cases can overlap with the H2 s bonding orbital to facilitate electron forward donation, forming bonding states between the Cu s-p-dz2 and H2 s bonding orbitals. The occupied Cu s-p-dxz/yz and s-p-dx2-y2 hybrid orbitals in the case of T(CuL3) promote the electron back donation to the H2 s* antibonding orbital, leading to the formation of bonding states. Conversely, in P(CuL4)2 coordination, the absence of such hybridization results in the lack of electron back donation. The complete Kubas interaction with both forward and back electron donations is responsible for a higher adsorption energy of 37.6 kJ/mol in the case of T(CuL3) than the value of 10.6 kJ/mol in the P(CuL4)2 coordination. © 2024, The Authors. All rights reserved.

关键词： Electronic structure

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Benefit from public unlabeled data: A Frangi filtering-based pretraining network for 3D cerebrovascular segmentation

arXiv

引用

arXiv 2023年

作者： Shi, Gen Lu, Hao Hui, Hui Tian, Jie School of Engineering Medicine School of Biological Science and Medical Engineering Beihang University Beijing100191 China Ministry of Industry and Information Technology of China Beijing100191 China State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academic of Science Beijing10086 China CAS Key Laboratory of Molecular Imaging Institute of Automation Chinese Academy of Sciences Beijing100190 China

The precise cerebrovascular segmentation in time-of-flight magnetic resonance angiography (TOF-MRA) data is crucial for clinically computer-aided diagnosis. However, the sparse distribution of cerebrovascular structures in TOF-MRA results in an exceedingly high cost for manual data labeling. The use of unlabeled TOF-MRA data holds the potential to enhance model performance significantly. In this study, we construct the largest preprocessed unlabeled TOF-MRA datasets (1510 subjects) to date. We also provide three additional labeled datasets totaling 113 subjects. Furthermore, we propose a simple yet effective pertraining strategy based on Frangi filtering, known for enhancing vessel-like structures, to fully leverage the unlabeled data for 3D cerebrovascular segmentation. Specifically, we develop a Frangi filtering-based preprocessing workflow to handle the large-scale unlabeled dataset, and a multi-task pretraining strategy is proposed to effectively utilize the preprocessed data. By employing this approach, we maximize the knowledge gained from the unlabeled data. The pretrained model is evaluated on four cerebrovascular segmentation datasets. The results have demonstrated the superior performance of our model, with an improvement of approximately 3% compared to state-of-the-art semi- and self-supervised methods. Furthermore, the ablation studies also demonstrate the generalizability and effectiveness of the pretraining method regarding the backbone structures. The code and data have been open source at: https://***/shigen-StoneRoot/FFPN. © 2023, CC BY.

关键词： Computer aided diagnosis

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Atmosphere air temperature forecasting using the honey badger optimization algorithm: on the warmest and coldest areas of the world

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Engineering Applications of Computational Fluid Mechanics 2023年第1期17卷

作者： Zhou, Jincheng Wang, Dan Band, Shahab S. Mirzania, Ehsan Roshni, Thendiyath School of Computer and Information Qiannan Normal University for Nationalities Duyun China Key Laboratory of Complex Systems and Intelligent Optimization of Guizhou Province Duyun China Key Laboratory of Complex Systems and Intelligent Optimization of Qiannan Duyun China School of Mathematics and Statistics Qiannan Normal University for Nationalities Duyun China Future Technology Research Center College of Future National Yunlin University of Science and Technology Douliou Taiwan Department of Water Engineering University of Tabriz Tabriz Iran Department of Civil Engineering National Institute of Technology Patna Bihar India

Precisely forecasting air temperature as a significant meteorological parameter has a critical role in environment quality management. Hence, this study employs a hybrid intelligent model for accurately monthly temperature forecasting for one to three times ahead in the hottest and coldest regions of the world. The hybrid model contains the artificial neural network (ANN) hybridized with the powerful hetaeristic Honey Badger Algorithm (HBA-ANN). The average mutual information (AMI) technique is employed to find the optimal time delay values for the temperature variable for different time horizons. Finally, the performance of the developed hybrid model is compared with the classical ANN and the Gene Expression Programming (GEP) using some statistical criteria, and the Taylor and scatter diagrams. Results indicated that in each time horizon, the HBA-ANN model with the lowest distance from observation points based on Taylor diagram, high values for NSE and R², and low values for RMSE, MAE, and RSR outperformed the ANN and GEP models in both training and testing phases. Hence, using the Honey Badger Algorithm could increase the accuracy of the model. This model's precise performance supports the case for it to be employed to forecast other environmental parameters. © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

关键词： Air temperature artificial neural network forecasting honey badger algorithm hybrid model warmest and coldest regions

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Three-dimensional third-order gas-kinetic scheme on hybrid unstructured meshes for Euler and Navier-Stokes equations

arXiv

引用

arXiv 2022年

作者： Yang, Yaqing Pan, Liang Xu, Kun Laboratory of Mathematics and Complex Systems School of Mathematical Sciences Beijing Normal University Beijing China Department of Mathematics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Shenzhen Research Institute Hong Kong University of Science and Technology Shenzhen China

In this paper, a third-order gas-kinetic scheme is developed on the three-dimensional hybrid unstructured meshes for the numerical simulation of compressible inviscid and viscous flows. In the classical weighted essentially non-oscillatory (WENO) scheme, the high-order spatial accuracy is achieved by the non-linear combination of lower order polynomials. However, for the hybrid unstructured meshes, the procedures, including the selection of candidate stencils and calculation of linear weights, become extremely complicated, especially for three-dimensional problems. To overcome the drawbacks, a third-order WENO reconstruction is developed on the hybrid unstructured meshes, including tetrahedron, pyramid, prism and hexahedron. A simple strategy is adopted for the selection of big stencil and sub-stencils, and the topologically independent linear weights are used in the spatial reconstruction. A unified interpolation is used for the volume integral of different control volumes, as well as the flux integration over different cell interfaces. Incorporate with the two-stage fourth-order temporal discretization, the explicit high-order gas-kinetic schemes are developed for unsteady problems. With the lower-upper symmetric Gauss-Seidel (LU-SGS) methods, the implicit high-order gas-kinetic schemes are developed for steady problems. A variety of numerical examples, from the subsonic to supersonic flows, are presented to validate the accuracy and robustness for both inviscid and viscous flows. To accelerate the computation, the current scheme is implemented with the graphics processing unit (GPU) using compute unified device architecture (CUDA). The speedup of GPU code suggests the potential of high-order gas-kinetic schemes for the large scale computation. Copyright © 2022, The Authors. All rights reserved.

关键词： Viscous flow

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Regularity of solutions to the Dirichlet problem for fast diffusion equations

arXiv

引用

arXiv 2022年

作者： Jin, Tianling Xiong, Jingang Department of Mathematics The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong School of Mathematical Sciences Laboratory of Mathematics and Complex Systems MOE Beijing Normal University Beijing100875 China

We prove global Hölder gradient estimates for bounded positive weak solutions of fast diffusion equations in smooth bounded domains with the homogeneous Dirichlet boundary condition, which then lead us to establish their optimal global regularity. This solves a problem raised by Berryman and Holland in *** Codes Primary 35B65, Secondary 35K59 Copyright © 2022, The Authors. All rights reserved.

关键词： Boundary conditions

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