检索结果-南通市图书馆

npj Computational Materials 2024年第1期10卷 2244-2256页

作者： Kang-Hyun Lee gun jin yun Department of Aerospace Engineering Seoul National UniversityGwanak-gu Gwanak-ro 1Seoul 08826South Korea Institute of Advanced Aerospace Technology Seoul National UniversityGwanak-gu Gwanak-ro 1Seoul 08826South Korea

Acquiring reliable microstructure datasets is a pivotal step toward the systematic design of materials with the aid of integrated computational materials engineering(ICME)***,obtaining three-dimensional(3D)microstructure datasets is often challenging due to high experimental costs or technical limitations,while acquiring two-dimensional(2D)micrographs is comparatively *** deal with this issue,this study proposes a novel framework called‘Micro3Diff’for 2D-to-3D reconstruction of microstructures using diffusion-based generative models(DGMs).Specifically,this approach solely requires pre-trained DGMs for the generation of 2D samples,and dimensionality expansion(2D-to-3D)takes place only during the generation process(i.e.,reverse diffusion process).

关键词： diffusion dimensionality expansion

A Self-Learning Data-Driven Development of Failure Criteria of Unknown Anisotropic Ductile Materials with Deep Learning Neural Network

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第2期66卷 1091-1120页

作者： Kyungsuk Jang gun jin yun Department of Aerospace Engineering Seoul National UniversitySeoul088262South Korea Institute of Advanced Aerospace Technology Seoul National UniversitySeoul08826South Korea

This paper first proposes a new self-learning data-driven methodology that can develop the failure criteria of unknown anisotropic ductile materials from the minimal number of experimental *** failure criteria of anisotropic ductile materials requires time-consuming tests and manual data *** proposed method can overcome such practical *** methodology is formalized by combining four ideas:1)The deep learning neural network(DLNN)-based material constitutive model,2)Self-learning inverse finite element(SELIFE)simulation,3)Algorithmic identification of failure points from the selflearned stress-strain curves and 4)Derivation of the failure criteria through symbolic regression of the genetic *** update and the algorithmic tangent operator were formulated in terms of DLNN parameters for nonlinear finite element ***,the SELIFE simulation algorithm gradually makes the DLNN model learn highly complex multi-axial stress and strain relationships,being guided by the experimental boundary *** the failure point identification,a self-learning data-driven failure criteria are eventually developed with the help of a reliable symbolic regression *** methodology and the self-learning data-driven failure criteria were verified by comparing with a reference failure criteria and simulating with different materials orientations,respectively.

关键词： Data-driven modeling deep learning neural networks genetic programming anisotropic failure criterion

Prediction of Melt Pool Dimension and Residual Stress Evolution with Thermodynamically-Consistent Phase Field and Consolidation Models during Re-Melting Process of SLM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第1期66卷 87-112页

作者： Kang-Hyun Lee gun jin yun Department of Aerospace Engineering Seoul National UniversitySeoul08826South Korea Institute of Advanced Aerospace Technology Seoul National UniversitySeoul08826South Korea

Re-melting process has been utilized to mitigate the residual stress level in the selective laser melting(SLM)process in recent ***,the complex consolidation mechanism of powder and the different material behavior after the first laser melting hinder the direct implementation of the re-melting *** this work,the effects of re-melting on the temperature and residual stress evolution in the SLM process are investigated using a thermo-mechanically coupled finite element *** degree of consolidation is incorporated in the energy balance equation based on the thermodynamically-consistent phase-field *** drastic change of material properties due to the variation of temperature and material state is also *** the proposed simulation framework,the single-track scanning is simulated first to predict the melt pool dimension and validate the proposed model with the existing experimental *** obtained thermal histories reveal that the highest cooling rate is observed at the end of the local solidification time which acts as an important indicator for the alleviation of temperature ***,the scanning of a whole single layer that consists of multiple tracks is simulated to observe the stress evolution with several re-melting *** the full melting of powder material in the first scanning process,the increase of residual stress level is observed with one remelting ***,the predicted stress level with the re-melting process shows the variation trend attributable to the accumulated heat in the *** numerical issues and the detailed implementation process are also introduced in this paper.

关键词： Selective laser melting thermo-mechanical analysis Ti-6Al-4V additive manufacturing re-melting residual stress

CaH2-promoted activity of Ni-carbonate interface for CO_(2) methanation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第1期100卷 522-532页

作者： jin-Peng Wang Guo-Cui Mao Hui-Lin Jiang Bao-Xia Dong yun-Lei Teng School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002JiangsuChina

Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic *** interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogenation reaction,involving surface carbonate hydrogenation and CO_(2)***,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic CO_(2)*** work demonstrated that the incorporation of CaH_(2)in Ni/CaCO_(3)enhances the CO_(2)methanation activity of the *** CO_(2)conversion for Ni/CaH_(2)-CaCO_(3)reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO_(3)(31.6%) and Ni/CaH_(2)-CaO (42.4%) ***,the Ni/CaH_(2)-CaCO_(3)catalysts remained stable during the stability test for 24 h at 400°C and 8 *** research revealed that CaH_(2)played a crucial role in promoting the activity of the Ni-carbonate interface for CO_(2)***_(2)could modify the electronic structure of Ni and tune the structural properties of CaCO_(3)to generate medium basic sites (OH groups),which are favorable for the activation of H2and CO_(2).In-situ Fourier transform infrared spectroscopy (FTIR) analysis combined with density functional theory calculations demonstrated that CO_(2)activation occurs at the hydroxyl group (OH) on the CaH_(2)-modified Ni-carbonate surface,leading to the formation of CO_(3)H****,our study has confirmed that CO_(2)methanation over the Ni/CaH_(2)-CaCO_(3)catalysts proceeds via the formate pathway.

关键词： CO_(2)methanation Metal hydride Ni catalysts Carbonate Metal-carbonate interface

Trinuclear gold-catalyzed site-selective alkylation of peptides

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 249-256页

作者： Qing-yun Fang Chengyihan Gu Yinghan Chen Wencheng Yan Yong Liang Weipeng Li Chengjian Zhu Jie Han jin Xie State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsChemistry and Biomedicine Innovation Center(ChemBIC)School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Green Catalysis Center College of ChemistryZhengzhou UniversityZhengzhou 450001China State Key Laboratory of Natural Medicines China Pharmaceutical UniversityNanjing 211198China

Selective modification of peptides has always been a challenging *** selective alkylation of peptides can alter the biological activity and physical properties of molecules,and it has gained significant research *** herein disclose an intriguing gold-catalyzed alkylation of peptides using bench-stable unactivated alkyl bromides under photoredox catalysis.A wide range of structurally diverse primary,secondary and tertiary alkyl bromides serve as effective coupling partners to precisely connect with theα-C(sp^(3))–H in glycine residue of *** protocol demonstrates an exceptionally broad scope for alkyl halides and excellent tolerance for a wide range of useful functional groups.A series of relay transformations to construct cyclic peptides,to proceed click reaction and to realize peptide fluorescence labeling further enhance its synthetic *** addition,mechanistic studies and density functional theory(DFT)calculations reveal an inner-sphere and subsequent outersphere single electron transfer(SET)mechanism.

关键词： gold catalysis peptide alkylation C-C coupling radical

同方期刊数据库

Target Search and Navigation in Heterogeneous Robot Systems with Deep Reinforcement Learning

在线全文

学校读者我要写书评

暂无评论

Machine Intelligence Research 2025年第1期22卷 79-90页

作者： yun Chen Jiaping Xiao Department of Mechanical Engineering University of AlabamaTuscaloosa35487USA School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore639798Singapore

Collaborative heterogeneous robot systems can greatly enhance the efficiency of target search and navigation *** this paper,we design a heterogeneous robot system consisting of an unmanned aerial vehicle(UAV)and an unmanned ground vehicle(UGV)for search and rescue missions in unknown *** system is able to search for targets and navigate to them in a maze-like mine environment with the policies learned through deep reinforcement learning *** the training process,if two robots are trained simultaneously,the rewards related to their collaboration may not be properly ***,we introduce a multi-stage reinforcement learning framework and a curiosity module to encourage agents to explore unvisited *** in simulation environments show that our framework can train the heterogeneous robot system to achieve the search and navigation with unknown target locations while existing baselines may *** UGV achieves a success rate of 89.1%in the mission within the original environment,and maintains a 67.6%success rate in untrained complex environments.

关键词： Heterogeneous intelligent systems deep reinforcement learning multiagent systems robot learning target search

Value Iteration-Based Distributed Adaptive Dynamic Programming for Multi-Player Differential Game With Incomplete Information

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2025年第2期12卷 436-447页

作者： yun Zhang Yuqi Wang yunze Cai the Department of Automation Shanghai Jiao Tong University the Key Laboratory of System Control and Information Processing Ministry of Education of China the National Key Laboratory of Air-based Information Perception and Fusion

In this paper, a distributed adaptive dynamic programming(ADP) framework based on value iteration is proposed for multi-player differential games. In the game setting,players have no access to the information of others' system parameters or control laws. Each player adopts an on-policy value iteration algorithm as the basic learning framework. To deal with the incomplete information structure, players collect a period of system trajectory data to compensate for the lack of information. The policy updating step is implemented by a nonlinear optimization problem aiming to search for the proximal admissible policy. Theoretical analysis shows that by adopting proximal policy searching rules, the approximated policies can converge to a neighborhood of equilibrium policies. The efficacy of our method is illustrated by three examples, which also demonstrate that the proposed method can accelerate the learning process compared with the centralized learning framework.

关键词： Distributed adaptive dynamic programming incomplete information multi-player differential game (MPDG) value iteration

Advancing gravitational theory through the tetrahedral constellation gravitational wave observatory

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 197-198页

作者： yun-Yong Wang Zhou-Jian Cao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing102206China

The Tetrahedral Constellation Gravitational Wave Observatory(TEGO)[1]represents a significant leap forward in gravitational wave detection,advancing our understanding of gravitational *** introducing a fourth spacecraft to form a tetrahedral configuration,TEGO enhances traditional triangular setups,enabling the simultaneous sensitivity to all six gravitational wave polarization modes,including those not predicted by general relativity.

关键词： wave polarization theory

同方期刊数据库

Sex-dependent alterations in extracellular vesicles linking chronic spinal cord injury to brain neuroinflammation and neurodegeneration

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第2期20卷 483-484页

作者： yun Li Junfang Wu Department of Anesthesiology&Shock Trauma and Anesthesiology Research(STAR)CenterUniversity of Maryland School of MedicineBaltimoreMDUSA

Traumatic spinal cord injury(SCI)is a devastating exogenous injury with long-lasting consequences and a leading cause of death and disability *** in assistive technology,rehabilitative interventions,and the ability to identify and intervene in secondary conditions have significantly increased the long-term survival rate of SCI patients,with some people even living well into their seventh or eighth *** survival changes have led neurotrauma researchers to examine how SCI interacts with brain *** health and epidemiological data showed that patients with long-term SCI can have a lower life expectancy and quality of life,along with a higher risk of comorbidities and complications.

关键词： alterations inflammation injury

Separation of the ionospheric and thermospheric contributions in the data from the Triple Ionosophere Photo Meter onboard the Feng-yun 3E satellite

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2025年第1期68卷 172-184页

作者： Fang JIANG Tian MAO jin-Song WANG Xiu-Qing HU Xiao-Xin ZHANG Liping FU Nan JIA Tianfang WANG National Space Science Center Chinese Academy of SciencesBeijing100090China Beijing Key Laboratory of Space Environment Exploration Beijing100090China Key Laboratory of Environmental Space Situation Awareness Technology Beijing100090China National Satellite Meteorological Center China Meteorological AdministrationBeijing100081China

The Triple Ionosphere Photo Meter(TRIPM)is a far ultraviolet nadir-view photometer that is onboard the secondgeneration,polar-orbiting Chinese meteorological satellite Feng-yun 3E(FY-3E),which was launched on July 5,*** has three channels,and each is used to measure different types of emissions:(1)135.6 nm airglow produced by the recombination of the O+ions and electrons in the absence of sunlight(nighttime channel);(2)135.6 nm airglow from the OI when sunlight is present(daytime/dusk-dawn 135.6 nm channel);and(3)Airglow in the N_(2)LBH of the TRIPM(daytime/dusk-dawn N_(2)LBH channel).FY-3E is a satellite operating in the early morning ***,the data are mostly distributed on the dawndusk side or at times when the solar zenith angle is relatively *** this study,combined with simulation calculations,the data are *** further explore the application value of the data products,a model is used to separate the ionospheric radiative recombination contribution from the thermosphere photoelectron impact excitation contribution in the data from the daytime/dusk-dawn 135.6 nm *** approach not only improves the accuracy of O/N_(2)derived from the 135.6 nm channel and N_(2)LBH channel but also provides the ionospheric 135.6 nm radiance at the same time as the *** results show that the 135.6 nm radiance originating from the combination of O+and electrons extracted from the measurement data exhibits similar equatorial anomaly peak structure characteristics and seasonal variations as the corresponding GPS total electron content(TEC)*** the other hand,the separated 135.6 nm radiance generated from the thermosphere photoelectron collision excitation does not contain radiative recombination contributions;thus,the ionosphere influence is greatly avoided when the O/N_(2)is obtained.

关键词： Far ultraviolet 135.6 nm emission intensity Photoelectron impact excitation Radiative recombination excitation

同方期刊数据库