检索结果-南通市图书馆

npj Computational Materials 2022年第1期8卷 455-466页

作者： Koushik Pal cheol woo park Yi Xia Jiahong Shen Chris Wolverton Department of Materials Science and Engineering Northwestern UniversityEvanstonIL60208USA

We design an advanced machine-learning(ML)model based on crystal graph convolutional neural network that is insensitive to volumes(i.e.,scale)of the input crystal structures to discover novel quaternary chalcogenides,AMM′Q3(A/M/M'=alkali,alkaline earth,post-transition metals,lanthanides,and Q=chalcogens).These compounds are shown to possess ultralow lattice thermal conductivity(κ_(l)),a desired requirement for thermal-barrier coatings and *** screening the thermodynamic stability of~1 million compounds using the ML model iteratively and performing density-functional theory(DFT)calculations for a small fraction of compounds,we discover 99 compounds that are validated to be stable in *** several DFT-stable compounds,we calculate theirκl using Peierls–Boltzmann transport equation,which reveals ultralowκ_(l)(<2 Wm^(−1)K^(−1)at room temperature)due to their soft elasticity and strong phonon *** work demonstrates the high efficiency of scale-invariant ML model in predicting novel compounds and presents experimental-research opportunities with these new compounds.

关键词： ultralow thermal invariant

New separation algorithm for touching grain kernels based on contour segments and ellipse fitting

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 Zhejiang University-Science C(Computers and Electronics) 2011年第1期12卷 54-61页

作者： Lei YAN cheol-woo park Sang-Ryong LEE Choon-Young LEE School of Mechanical Engineering Kyungpook National University Daegu 702-701 Korea School of Technology Beijing Forestry University Beijing 100083 China

A new separation algorithm based on contour segments and ellipse fitting is proposed to separate the ellipse-like touching grain kernels in digital *** image is filtered and converted into a binary image *** the contour of touching grain kernels is extracted and divided into contour segments (CS) with the concave points on *** next step is to merge the contour segments,which is the main contribution of this *** distance measurement (DM) and deviation error measurement (DEM) are proposed to test whether the contour segments pertain to the same kernel or *** they pass the measurement and judgment,they are merged as a new *** with these newly merged contour segments,the ellipses are fitted as the representative ellipses for touching *** verify the proposed algorithm,six different kinds of Korean grains were *** results showed that the proposed method is efficient and accurate for the separation of the touching grain kernels.

关键词： Separation algorithm Touching grains Contour segments Ellipse fitting

Accurate and scalable graph neural network force field and molecular dynamics with direct force architecture

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2021年第1期7卷 650-658页

作者： cheol woo park Mordechai Kornbluth Jonathan Vandermause Chris Wolverton Boris Kozinsky Jonathan P.Mailoa Robert Bosch Research and Technology Center CambridgeMA 02139USA Northwestern University EvanstonIL 60208USA Harvard School of Engineering and Applied Sciences CambridgeMA 02138USA

Recently,machine learning(ML)has been used to address the computational cost that has been limiting ab initio molecular dynamics(AIMD).Here,we present GNNFF,a graph neural network framework to directly predict atomic forces from automatically extracted features of the local atomic environment that are translationally-invariant,but rotationally-covariant to the coordinate of the *** demonstrate that GNNFF not only achieves high performance in terms of force prediction accuracy and computational speed on various materials systems,but also accurately predicts the forces of a large MD system after being trained on forces obtained from a smaller ***,we use our framework to perform an MD simulation of Li7P3S11,a superionic conductor,and show that resulting Li diffusion coefficient is within 14%of that obtained directly from *** high performance exhibited by GNNFF can be easily generalized to study atomistic level dynamics of other material systems.

关键词： neural AIMD dynamics

Recent advances and applications of deep learning methods in materials science

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 548-573页

作者： Kamal Choudhary Brian DeCost Chi Chen Anubhav Jain Francesca Tavazza Ryan Cohn cheol woo park Alok Choudhary Ankit Agrawal Simon J.L.Billinge Elizabeth Holm Shyue Ping Ong Chris Wolverton Materials Science and Engineering Division National Institute of Standards and TechnologyGaithersburgMD20899USA Theiss Research La JollaCA92037USA DeepMaterials LLC Silver SpringMD20906USA Material Measurement Science Division National Institute of Standards and TechnologyGaithersburgMD20899USA Department of NanoEngineering University of California San DiegoSan DiegoCA92093USA Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCAUSA Department of Materials Science and Engineering Carnegie Mellon UniversityPittsburghPA15213USA Department of Materials Science and Engineering Northwestern UniversityEvanstonIL60208USA Department of Electrical and Computer Engineering Northwestern UniversityEvanstonIL60208USA Department of Applied Physics and Applied Mathematics and the Data Science Institute Fu Foundation School of Engineering and Applied SciencesColumbia UniversityNew YorkNY10027USA

Deep learning(DL)is one of the fastest-growing topics in materials data science,with rapidly emerging applications spanning atomistic,image-based,spectral,and textual data *** allows analysis of unstructured data and automated identification of *** recent development of large materials databases has fueled the application of DL methods in atomistic prediction in *** contrast,advances in image and spectral data have largely leveraged synthetic data enabled by high-quality forward models as well as by generative unsupervised DL *** this article,we present a high-level overview of deep learning methods followed by a detailed discussion of recent developments of deep learning in atomistic simulation,materials imaging,spectral analysis,and natural language *** each modality we discuss applications involving both theoretical and experimental data,typical modeling approaches with their strengths and limitations,and relevant publicly available software and *** conclude the review with a discussion of recent cross-cutting work related to uncertainty quantification in this field and a brief perspective on limitations,challenges,and potential growth areas for DL methods in materials science.

关键词： learning limitations textual

Numerical Study of RBC Motion and Deformation through Microcapillary in Alcohol Plasma Solution

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Fluid Dynamics 2015年第1期5卷 26-33页

作者： Aleksey Ni Taqi Ahmad Cheema cheol woo park School of Mechanical Engineering Kyungpook National University Daegu Korea Department of Mechanical Engineering GIK Institute of Engineering Sciences and Technology Topi Pakistan

Alcohol influences human health condition by starving red blood cells (RBCs) of oxygen, which results in poor blood circulation. Starved RBCs clump together and restrict blood flow, especially in capillaries. In this study, a finite element method-based moving mesh technique was applied to simulate the motion and deformation of a single RBC under different flow conditions. A 2-D model of a single RBC floating in plasma-alcohol solution was created using Arbitrary Lagrangian-Eulerian (ALE) method with moving mesh for a fluid structure interaction problem. Cell deformability and stability were studied in an alcoholic plasma solution at different fluid flow conditions. Poor blood circulation was observed with RBC tending to rotate and oscillate at low flow rates. Moreover, RBC exhibited a parachute shape while moving without oscillation, which indicated improved micro-circulation at increased flow rates. In both cases, RBC exhibited a parachute shape while moving through micro-channel at increased flow rates. The simulation also showed the significant increase of RBC deformability with the increasing viscosity of plasma as a result of alcohol presence in blood.

关键词： Moving Mesh Fluid Structure Interaction Alcohol RBC Microvessel Deformability Micro-Circulation

Finite Element Analysis of Tire Traction Using a Rubber-Ice Friction Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2018年第11期8卷 495-505页

作者： Hyun Chul Jung woo cheol park Kyoung Moon Jeong R&D Center Kumho Tire Co. Inc. Yongin South Korea

The friction of road surface covered by snow or ice is very low and that results in reducing vehicle traction forces and potential traffic accidents. In general, to establish a master curve on a rubber-ice friction model is difficult because the ice surface, being not far removed from its melting point, reacts itself very sen-sitively to pressure, speed, and temperature changes. In this paper, an accepta-ble frictional interaction model was implemented to finite element method to rationally examine the frictional interaction behavior on ice between the tire and the road surface. The formula of friction characteristic according to tem-perature and sliding velocity on the ice surface was applied for tire traction analysis. Numerical results were verified by comparing the outdoor test data and it was confirmed to indicate similar correlation. It is found that the rub-ber-ice friction model will be useful for the improvement of the ice traction performance of tire.

关键词： Tire Ice Surface Finite Element Method Frictional Model Temperature Slid-ing Velocity

The Effect of Tire Design Parameters on the Force Transmissibility

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2018年第10期8卷 446-458页

作者： woo cheol park Hee Kyu Lim Kyoung Moon Jeong Tan Wan Kim R&D Center KUMHO TIRE Co. Inc. Yongin South Korea

A finite element modeling technique is employed in this paper to predict the force transmissibility of tire-cavity-wheel assembly under a free-fixed condition. The tire and wheel force transmissibility is factor in structure borne road noise performance. In order to improve structure borne noise, it is required to lower the 1st peak frequency of force transmissibility. This paper presents an application of finite element analysis modeling along with experimental verification to predict the force transmissibility of tire and wheel assembly. The results of finite element analysis for force transmissibility are shown to be in good agreement with the results from the indoor test. In order to improve structure borne noise, it is required to lower the 1st peak frequency of force transmissibility. And, the effect of the tire design parameters such as the density and modulus of a rubber and the cord stiffness on the force transmissibility is discussed. It is found that the prediction of the force transmissibility model using finite element analysis will be useful for the improvement of the road noise performance of passenger car tire.

关键词： Force Transmissibility Tire-Cavity-Wheel Assembly Design Parameter Finite Element Analysis Noise

Numerical Study on the Effects of Contraction Ratio in a Two-Phase Flow Injection Nozzle

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Fluid Dynamics 2016年第1期6卷 1-10页

作者： Haider Ali Kyung Won Kim Jae Sik Kim Jong Yun Choi cheol woo park School of Mechanical Engineering Kyungpook National University Daegu Korea Podomaul Co. Ltd. 1190 Kumchang-Ro Daechang-Myon Yeongcheon-Si Korea B.C.M. Co. Ltd. 81 Yeomsaekgongdancheon-Ro Seo-Gu Daegu Korea

The Euler-Euler numerical method was used to investigate the effects of contraction ratio on twophase flow mixing with mass transfer in the flow injection nozzle. The geometric shape of the nozzle was modified to improve carbonation efficiency. A gas inlet hole was created to increase the flow mixing of CO2 with water. A nozzle throat was also introduced to increase the gas dissolution by increasing flow rates. Various contraction ratios of nozzle throat, inlet gas and liquid velocities, and gas bubble sizes were employed to determine their effects on gas hold-up, gas concentration, and mass transfer coefficient. Results revealed that the flow injection nozzle with high contraction ratios improved carbonation because of high gas hold-up. Gas concentration was directly related to contraction ratio and gas flow velocities. Carbonation reduced when high liquid velocities and large gas bubbles were employed because of inefficient flow mixing. This study indicated that flow injection nozzle with large contraction ratios were suitable for carbonation because of their ability to increase gas hold-up, gas concentration, and mass transfer coefficient.

关键词： Flow Injection Nozzle Nozzle Throat Contraction Ratio Gas-Liquid Flow Mass Transfer

CORE:Common Region Extension Based Multiple Protein Structure Alignment for Producing Multiple Solution

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 Computer Science & Technology 2013年第4期28卷 647-656页

作者： woo-cheol Kim Sanghyun park Jung-Im Won College of Information Sciences and Technology The Pennsylvania State University University Park Department of Computer Science Yonsei University Research Center of Information and Electronic Engineering Hallym University Chuncheon

Over the past several decades, biologists have conducted numerous studies examining both general and specific functions of proteins. Generally, if similarities in either the structure or sequence of amino acids exist for two proteins, then a common biological function is expected. Protein function is determined primarily based on the structure rather than the sequence of amino acids. The algorithm for protein structure alignment is an essential tool for the research. The quality of the algorithm depends on the quality of the similarity measure that is used, and the similarity measure is an objective function used to determine the best alignment because of their individual strength and weakness However, none of existing similarity measures became golden standard They require excessive filtering to find a single alignment. In this paper, we introduce a new strategy that finds not a single alignment, but multiple alignments with different lengths. This method has obvious benefits of high quality alignment. However, this novel method leads to a new problem that the running time for this method is considerably longer than that for methods that find only a single alignment. To address this problem~ we propose algorithms that can locate a common region （CORE） of multiple alignment candidates, and can then extend the CORE into multiple alignments. Because the CORE can be defined from a final alignment, we introduce CORE＊ that is similar to CORE and propose an algorithm to identify the CORE＊. By adopting CORE＊ and dynamic programming, our proposed method produces multiple alignments of various lengths with higher accuracy than previous methods. In the experiments, the alignments identified by our algorithm are longer than those obtained by TM-align by 17% and 15.48%, on average, when the comparison is conducted at the level of super-family and fold, respectively.

关键词： structure alignment similarity search protein structure

Use of a Digital Image Correlation Technique for Measuring the Material Properties of Beetle Wing

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2009年第3期6卷 224-231页

作者： Tailie Jin Nam Seo Goo Sung-Choong woo Hoon cheol park Biomemitics and Intelligent Microsystem Laboratory Department of Advanced Technology FusionKonkuk University

Beetle wings are very specialized flight organs consisting of the veins and *** it is necessary from a bionic view to investigate the material properties of a beetle wing *** the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing *** were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing *** specimen was attached to a designed fixture to induce a uniform displacement by means of a *** used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a *** thickness of the beetle wing varied at different points of the *** elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 *** a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle *** addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile *** result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.

关键词： digital image correlation technique beetle wing elastic modulus Poisson's ratio vein membrane