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Theoretical analysis on elastic buckling of nanobeams based on stress-driven nonlocal integral model

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Applied Mathematics and Mechanics(English Edition) 2020年第2期41卷 207-232页

作者： peng JIANG Hai qing Cunfa gao State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Several studies indicate that Eringen's nonlocal model may lead to some inconsistencies for both Euler-Bernoulli and Timoshenko beams, such as cantilever beams subjected to an end point force and fixed-fixed beams subjected a uniform distributed load. In this paper, the elastic buckling behavior of nanobeams, including both EulerBernoulli and Timoshenko beams, is investigated on the basis of a stress-driven nonlocal integral model. The constitutive equations are the Fredholm-type integral equations of the first kind, which can be transformed to the Volterra integral equations of the first kind. With the application of the Laplace transformation, the general solutions of the deflections and bending moments for the Euler-Bernoulli and Timoshenko beams as well as the rotation and shear force for the Timoshenko beams are obtained explicitly with several unknown constants. Considering the boundary conditions and extra constitutive constraints, the characteristic equations are obtained explicitly for the Euler-Bernoulli and Timoshenko beams under different boundary conditions, from which one can determine the critical buckling loads of nanobeams. The effects of the nonlocal parameters and buckling order on the buckling loads of nanobeams are studied numerically, and a consistent toughening effect is obtained.

关键词： Laplace transformation Volterra integral equation Fredholm integral equation stress-driven nonlocal integral model

Self-Consistent Flow Shear Induced by Drift-Thermal Turbulence

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Chinese Physics Letters 1996年第8期13卷 598-601页

作者： peng Xiao-dong gao qing-di Southwestern Institute of Physics Chengdu 610041

The self-consistent poloidal flow shear induced by turbulence driven by impurity radiation has been studied analytically. A set of reduced equations is obtained. In our system, three equilibrium states exist. The first is the zero flow shear state, which is relevant to the behavior such as L mode, the second is the positive flow shear state, which is relevant to the behavior such as dithering H mode, and the third is the negative flow shear state, which is relevant to the behavior such as edge-localized modes.

关键词： flow Shear turbulence

Decoupling effects of driving factors on sediment yield in the Chinese Loess Plateau

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International Soil and Water Conservation Research 2023年第1期11卷 60-74页

作者： Xiaojing Tian Guangju Zhao Xingmin Mu pengfei Zhang peng gao wenyi Sun Xiaoyan Lu peng Tian State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F University26 Xinong RoadYangling712100Shaanxi ProvinceChina Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources26 Xinong RoadYangling712100Shaanxi ProvinceChina Yangtze Ecology and Environment Co Ltd.Wuhan430000Hubei ProvinceChina Erdos Hydrological Survey Bureau of Inner Mongolia Autonomous Region Erdos017010Inner MongoliaChina College of Natural Resources and Environment Northwest A&F University3 Taicheng RoadYangling712100Shaanxi ProvinceChina

Investigations of runoff and sediment yield changes and their relationships with potential driving factors provide good insights for understanding the mechanisms of hydrological *** study attempted to present a comprehensive investigation on the spatiotemporal variations of sediment yield in the Loess Plateau using continuous observed data at 46 hydrological stations during 1961-2016,and its responses to changes of precipitation,land use/cover and vegetation cover were analyzed by using the Partial Least Squares-Structural Equation Model(PLS-SEM).The results indicated that sediment yield reduced pro-nouncedly during 1961-2016 in the Loess Plateau,and 77.9%of this variation was explained by the combined effects of precipitation,land-use change,vegetation dynamics and runoff *** effects of precipitation,land-use change,and vegetation cover on sediment yield were 0.242,-0.528 and-0.630(P<0.05),respectively,and direct effect of runoff on sediment yield was 0.833(P<0.05).According to the Pearson Correlation Coefficient,the strongest positive correlation existed between annual sediment yield and runoff(r=0.88,P<0.05),followed by vegetation cover(r=-0.47,P<0.05)and land-use change(*** land and grassland)suggesting their significant trapping effects on soil ***,lower correlations were examined between sediment yield and precipitation indices(-0.14

关键词： Sediment yield Driving factors Correlation analysis PLS-SEM Loess Plateau

Rapid assembling organ prototypes with controllable cell-laden multi-scale sheets

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Bio-Design and Manufacturing 2019年第1期2卷 1-9页

作者： qing gao peng Zhao Ruijian Zhou peng Wang Jianzhong Fu Yong He Slate Key Laboratory of Fluid Power and Mechatronic Systems. School of Mechanical Engineering. Zhejiang University. Hangzhou 310027. China Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province. School of Mechanical Engineering Zhejiang University Hangzhou 310027 China

A native organ has heterogeneous structures, sirength, and cell components. It is a big challenge to fabricate organ prototypes with controllable shapes, strength, and cells. Herein, a hybrid method is developed to fabricate organ prototypes with controlled cell deposition by integrating extrusion-based 3D printing, electrospinning, and 3D bioprinting. Multi-scale sheets were first fabricated by 3D printing and electrospinning;then, all the sheets were assembled into organ prototypes by sol-gel react io n duri ng bioprinting. With this method, macroscale structures fabricated by 3D printing ensure the customized structures and provide mechanical support, nanoscale structures fabricated by electrospinning offer a favorable environment for cell growth, and different types of cells with controllable densities are deposited in accurate locations by bioprinting. The results show that L929 mouse fibroblasts encapsulated in the structures exhibited over 90% survival within 10 days and maintai ned a high proliferation rate. Furthermore, the cells grew in spherical shapes first and then migrated to the nano scale fibers showing stretched morphology. Additionally, a branched vascular structure was successfully fabricated using the presented method. Compared with other methods, this strategy offers an easy way to simultancously realize the shape control, nanolibrous structures, and cell accurate deposition, which will have potemidi applications in tissue cngineering.

关键词： Organ prototypes 3D printing Electrospinning 3D bioprinting Multi-scale sheets

Parameter optimization model in electrical discharge machining process

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 104-108页

作者： qing gao Qin-he ZHANG Shu-peng SU Jian-hua ZHANG School of Mechanical Engineering Shandong University Jinan 250061 China

Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and time consuming. In this paper, artificial neural network (ANN) and genetic algorithm (GA) are used together to establish the parameter optimization model. An ANN model which adapts Levenberg-Marquardt algorithm has been set up to represent the relationship between material removal rate (MRR) and input parameters, and GA is used to optimize parameters, so that optimization results are obtained. The model is shown to be effective, and MRR is improved using optimized machining parameters.

关键词： Electrical discharge machining (EDM) Genetic algorithm (GA) Artificial neural network (ANN) Levenberg- Marquardt algorithm

Sports video summarization and adaptation for application in mobile communication

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第5期7卷 819-829页

作者： gao Wen HUANG qing-ming JIANG Shu-qiang ZHANG peng Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100039 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China

Sports video appeals to large audiences due to its high commercial potentials. Automatically extracting useful semantic information and generating highlight summary from sports video to facilitate users' accessing requirements is an important problem, especially in the forthcoming broadband mobile communication and the need for users to access their multimedia information of interest from anywhere at anytime with their most convenient digital equipments. A system to generate highlight summaries oriented for mobile applications is introduced, which includes highlight extraction and video adaptation. In this system, several highlight extraction techniques are provided for field sports video and racket sports video by using multi-modal information. To enhance users' viewing experience and save bandwidth, 3D animation from highlight segment is also generated. As an important procedure to make video analysis results universally applicable, video transcoding techniques are applied to adapt the video for mobile communication environment and user preference. Experimental results are encouraging and show the advantage and feasibility of the system for multimedia content personalization, enhancement and adaptation to meet different user preference and network/device requirements.

关键词： Adaptive systems Animation Bandwidth Equipment Multimedia systems Requirements engineering Semantics Three dimensional

A Four-Fluid Model and Analysis of m=1 Internal Kink Instability

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Chinese Physics Letters 1999年第6期16卷 423-425页

作者： QU Hong-peng gao qing-di SHI Eing-ren Southwest Institute of Physics P.O.Box 432Chengdu 610041

Starting from the four-Huid equation which can simply and effectively describe the motion of trapped particles,we derive the eigenmode equations and the dispersion relation for m=1 internal kink mode with the effects of trapped particles,diamagnetic drifts,finite resistivity and anomalous electron viscosity ***,using those results,we Gnd the trapped particles effects have substantial influence on m=l internal kink mode in the cases with and without high-energy alpha particles in the core plasma.

关键词： viscosity simply resistivity

Structure-based Screening for the Non-zinc-chelating Selective MMP-13 Inhibitors of Natural Products

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Chinese Journal of Structural Chemistry 2020年第11期39卷 1990-2000页

作者： ZOU qing gao Qiu-Shuang YAO peng YAO Qi-Zheng ZHANG Ji Department of Physical Chemistry China Pharmaceutical UniversityNanjing 210009China State Key Laboratory of Natural Medicines China Pharmaceutical UniversityNanjing 210009China School of Pharmacy China Pharmaceutical UniversityNanjing 210009China

Matrix metalloproteinase-13(MMP-13) has been considered as a promising therapeutic target for osteoarthritis. In this work, the experimental crystal structures of five MMP-13-ligand complexes are used to build the multiple structure-based pharmacophore model of MMP-13 inhibitors. The reliability of pharmacophore model is validated using a decoy set. The pharmacophore model contains four chemical features: two hydrogen bond acceptor(HBA), one hydrophobic(HY) feature, and one ring aromatic(RA) feature. Particularly, the HY feature is found to orient the MMP-13 inhibitors deep into the S1’ pocket of MMP-13 to produce selective inhibition. By carrying out the screening of pharmacophore model and subsequent molecular docking, the four non-zinc-chelating selective MMP-13 inhibitors of natural products(NP-015973, NP-000814, STOCK1 N-24933, and STOCK1 N-69443) are identified. It is found that the binding modes of MMP-13 with our screened four natural products are very similar to the reported experimental binding mode of MMP-13 with the most active inhibitor(GG12003, IC50: 0.67 n M), and each of them involves the interactions of a ligand with the three amino acid residues Thr226, Lys119, and His201 of MMP-13 receptor. This shows that our modeling results are in good agreement with the relevant experimental results, which strongly supports our screened MMP-13 inhibitors of natural products. These screened natural products may be used as the lead compounds of MMP-13 inhibitors in the future studies of structural modifications.

关键词： matrix metalloproteinase-13 non-zinc-chelating inhibitor of MMP-13 pharmacophore model molecular docking screening

MPI-RCDD: A Framework for MPI Runtime Communication Deadlock Detection

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Journal of Computer Science & Technology 2020年第2期35卷 395-411页

作者： Hong-Mei Wei Jian gao peng qing Kang Yu Yan-Fei Fang Ming-Lu Li Department of Computer Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Jiangnan Institute of Computing Technology Wuxi 214083China

The message passing interface (MPI) has become a de facto standard for programming models of highperformance computing, but its rich and flexible interface semantics makes the program easy to generate communication deadlock, which seriously affects the usability of the system. However, the existing detection tools for MPI communication deadlock are not scalable enough to adapt to the continuous expansion of system scale. In this context, we propose a framework for MPI runtime communication deadlock detection, namely MPI-RCDD, which contains three kinds of main mechanisms. Firstly, MPI-RCDD has a message logging protocol that is associated with deadlock detection to ensure that the communication messages required for deadlock analysis are not lost. Secondly, it uses the asynchronous processing thread provided by the MPI to implement the transfer of dependencies between processes, so that multiple processes can participate in deadlock detection simultaneously, thus alleviating the performance bottleneck problem of centralized analysis. In addition, it uses an AND⊕OR model based algorithm named AODA to perform deadlock analysis work. The AODA algorithm combines the advantages of both timeout-based and dependency-based deadlock analysis approaches, and allows the processes in the timeout state to search for a deadlock circle or knot in the process of dependency transfer. Further, the AODA algorithm cannot lead to false positives and can represent the source of the deadlock accurately. The experimental results on typical MPI communication deadlock benchmarks such as Umpire Test Suit demonstrate the capability of MPIRCDD. Additionally, the experiments on the NPB benchmarks obtain the satisfying performance cost, which show that the MPI-RCDD has strong scalability.

关键词： high-performance computing message passing interface(MPI) communication deadlock deadlock detection AND⊕OR model