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Buckling analysis of functionally graded nanobeams under non-uniform temperature using stress-driven nonlocal elasticity

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Applied Mathematics and Mechanics(English Edition) 2022年第3期43卷 355-370页

作者： chi xu Yang LI Mingyue LU Zhendong DAI College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Provincial Key Laboratory of Bionic Functional Materials Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In this work,the size-dependent buckling of functionally graded(FG)Bernoulli-Euler beams under non-uniform temperature is analyzed based on the stressdriven nonlocal elasticity and nonlocal heat *** utilizing the variational principle of virtual work,the governing equations and the associated standard boundary conditions are systematically extracted,and the thermal effect,equivalent to the induced thermal load,is explicitly assessed by using the nonlocal heat conduction *** stressdriven constitutive integral equation is equivalently transformed into a differential form with two non-standard constitutive boundary *** employing the eigenvalue method,the critical buckling loads of the beams with different boundary conditions are *** numerically predicted results reveal that the growth of the nonlocal parameter leads to a consistently strengthening effect on the dimensionless critical buckling loads for all boundary ***,the effects of the influential factors pertinent to the nonlocal heat conduction on the buckling behavior are carefully examined.

关键词： size effect stress-driven nonlocal model constitutive boundary condition nonlocal heat conduction functionally graded(FG)beam buckling load

siRNA-mediated DNA methylation and H3K9 dimethylation in plants

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Protein & Cell 2013年第9期4卷 656-663页

作者： chi xu Jing Tian Beixin Mo College of Life Science Shenzhen Key Laboratory of Microbial Genetic EngineeringShenzhen UniversityShenzhen 518060China College of Life Science Shenzhen Key Laboratory of Marine Biological Resources and Ecological EnvironmentShenzhen UniversityShenzhen 518060China

Heterochromatic siRNAs regulate transcriptional gene silencing by inducing DNA methylation and histone H3K9 *** advances have revealed the distinct phases involved in siRNA mediated silencing pathway,although the precise functions of a number of factors remain undesignated,putative mechanisms for the con-nection between DNA and histone methylation have been investigated,and much effort has been invested to understand the biological functions of siRNA-mediated epigenetic modifi *** this review,we summarize the mechanism of siRNA-mediated epigenetic modification,which involves the production of siRNA and the recruit-ments of DNA and histone methytransferases to the target sequences assisted by complementary pairing between 24-nt siRNAs and nascent scaffold RNAs,the roles of siRNA-mediated epigenetic modifi cation in maintaining genome stability and regulating gene expression have been dis-cussed,newly identified players of the siRNA mediated silencing pathway have also been introduced.

关键词： epigenetic DNA methylation histone meth-ylation heterochromatic siRNA argonaute

Mixed Reality-based Interactive Technology for Aircraft Cabin Assembly

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chinese Journal of Mechanical Engineering 2009年第3期22卷 403-409页

作者： LI Shiqi PENG Tao WANG Junfeng xu chi School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Due to the narrowness of space and the complexity of structure, the assembly of aircraft cabin has become one of the major bottlenecks in the whole manufacturing process. To solve the problem, at the beginning of aircraft design, the different stages of the lifecycle of aircraft must be thought about, which include the trial manufacture, assembly, maintenance, recycling and destruction of the product. Recently, thanks to the development of the virtual reality and augmented reality, some low-cost and fast solutions are found for the product assembly. This paper presents a mixed reality-based interactive technology for the aircraft cabin assembly, which can enhance the efficiency of the assemblage in a virtual environment in terms of vision, information and operation. In the mixed reality-based assembly environment, the physical scene can be obtained by a camera and then generated by a computer. The virtual parts, the features of visual assembly, the navigation information, the physical parts and the physical assembly environment will be mixed and presented in the same assembly scene. The mixed or the augmented information will provide some assembling information as a detailed assembly instruction in the mixed reality-based assembly environment. Constraint proxy and its match rules help to reconstruct and visualize the restriction relationship among different parts, and to avoid the complex calculation of constraint＇s match. Finally, a desktop prototype system of virtual assembly has been built to assist the assembly verification and training with the virtual hand.

关键词： virtual assembly human-computer interaction mixed reality information augmentation constraints navigation

Industrial Wireless Control Networks:From WIA to the Future

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Engineering 2022年第1期8卷 18-24页

作者： Haibin Yu Peng Zeng chi xu State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China Key Laboratory of Networked Control Systems Chinese Academy of SciencesShenyang 110016China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang 110169China

*** Industrial automation is undergoing a significant innovation as information,communication,and operation technologies are deeply integrating with each *** this trend,industrial wireless control networks(IWCNs)are becoming increasingly attractive to industrial automation since they can help speed up production efficiency,reduce cost,enhance safety,and finally realize intelligent manufacturing[1].

关键词： attractive integrating becoming

Soil salt leaching under different irrigation regimes: HYDRUS-1D modelling and analysis

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Journal of Arid Land 2014年第1期6卷 44-58页

作者： WenZhi ZENG chi xu JingWei WU JieSheng HUANG State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

Field irrigation experiments were conducted in the Hetao Irrigation District of Inner Mongolia,china,to study the effects of irrigation regimes on salt leaching in the soil *** data were used to calibrate and validate the HYDRUS-1D *** results demonstrated that the model can accurately simulate the water and salt dynamics in the soil *** HYDRUS-1D model was then used to simulate 15 distinct irrigation *** results of the simulation indicated that irrigation amount did not have a significant effect on soil water storage but that increases in irrigation amount could accelerate salt ***,when the irrigation amount was larger than 20 cm,the acceleration was not *** with irrigating only once,intermittent irrigation had a better effect on increasing soil water storage and salt leaching,but excessive irrigation times and intervals did not improve salt *** addition,we found that the irrigation regime of 20 cm,irrigated twice at 1-d intervals,might significantly increase salt leaching in the plough layer and decrease the risks of deep seepage and groundwater contamination.

关键词： numerical simulation optimal irrigation regime secondary salinization water and salt dynamics

User Role Discovery and Optimization Method Based on K-means++ and Reinforcement Learning in Mobile Applications

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Computer Modeling in Engineering & Sciences 2022年第6期131卷 1365-1386页

作者： Yuanbang Li Wengang Zhou chi xu Yuchun Shi School of Computer Science and Technology Zhoukou Normal UniversityZhoukou466001China

With the widespread use of mobile phones,users can share their location and activity anytime,anywhere,as a form of check-in *** data reflect user ***-term stability and a set of user-shared features can be abstracted as user *** role is closely related to the users’social background,occupation,and living *** study makes four main contributions to the ***,user feature models from different views for each user are constructed from the analysis of the check-in ***,the K-means algorithm is used to discover user roles from user ***,a reinforcement learning algorithm is proposed to strengthen the clustering effect of user roles and improve the stability of the clustering ***,experiments are used to verify the validity of the *** results show that the method can improve the effect of clustering by 1.5∼2 times,and improve the stability of the cluster results about 2∼3 times of the *** method is the first time to apply reinforcement learning to the optimization of user roles in mobile applications,which enhances the clustering effect and improves the stability of the automatic method when discovering user roles.

关键词： User role discovery user role optimization K-means++ reinforcement learning

Observing spectral characteristics over a continental shelf and slope in the South china Sea

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Acta Oceanologica Sinica 2013年第7期32卷 29-37页

作者： SHANG Xiaodong xu chi CHEN Guiying WU Lixin State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of Sciences Institute of Acoustics Chinese Academy of Sciences

Using in situ measurement data from May-June, 1998, and data from the Asian seas international acoustics experiment （ASIAEX） from 2001 in the South china Sea （SCS）, the spectral density function and the dissipa- tion spectrum function are estimated. In the inffa-gravity wave （IGW） band, the power spectra of velocity （u, v, w） are universal functions with respect to characteristic frequencies, which correspond to the peak fre- quencies of the dissipation spectrum （PFDS）. This suggests that high-frequency internal waves in the IGW band have similar dynamical characteristics. In addition, the evolution of these characteristic frequencies is explored and its highest value is 8.8 cph （cycles per hour, 1 cph=2.778× 10-3 Hz）.

关键词： dissipation spectra,characteristic frequencies South china Sea

Metabolic landscape in cardiac aging:insights into molecular biology and therapeutic implications

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Signal Transduction and Targeted Therapy 2023年第4期8卷 1610-1629页

作者： Saiyang Xie Si-chi xu Wei Deng Qizhu Tang Department of Cardiology Renmin Hospital of Wuhan UniversityHubei Key Laboratory of Metabolic and Chronic DiseasesCardiovascular Research Institute of Wuhan UniversityWuhanPR China State Key Laboratory of Complex Severe and Rare Diseases Department of CardiologyPeking Union Medical College HospitalChinese Academy of Medical Science and Peking Union Medical CollegeBeijingPR China Department of Cardiology Renmin Hospital of Wuhan UniversityDepartment of CardiologyThe Fifth Affiliated Hospital of Xinjiang Medical UniversityÜrümqiPR China

Cardiac aging is evident by a reduction in function which subsequently contributes to heart *** metabolic microenvironment has been identified as a hallmark of malignancy,but recent studies have shed light on its role in cardiovascular diseases(CVDs).Various metabolic pathways in cardiomyocytes and noncardiomyocytes determine cellular senescence in the aging *** alteration is a common process throughout cardiac ***,the involvement of cellular senescence in cardiac injuries,including heart failure and myocardial ischemia and infarction,has been ***,metabolic complexity among human aging hearts hinders the development of strategies that targets metabolic *** over the past decade have linked cellular senescence and function with their metabolic reprogramming pathway in cardiac aging,including autophagy,oxidative stress,epigenetic modifications,chronic inflammation,and myocyte systolic phenotype *** addition,metabolic status is involved in crucial aspects of myocardial biology,from fibrosis to hypertrophy and chronic ***,further elucidation of the metabolism involvement in cardiac degeneration is still ***,deciphering the mechanisms underlying how metabolic reprogramming impacts cardiac aging is thought to contribute to the novel interventions to protect or even restore cardiac function in aging ***,we summarize emerging concepts about metabolic landscapes of cardiac aging,with specific focuses on why metabolic profile alters during cardiac degeneration and how we could utilize the current knowledge to improve the management of cardiac aging.

关键词： cardiac degeneration involvement

Two-Layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in the Wellbore

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Computer Modeling in Engineering & Sciences 2020年第4期123卷 75-100页

作者： Min Luo Tingting xu Jiajun Jiang xu chi Jing Wang Shihua xue Mechanical Science and Engineering College Northeast Petroleum UniversityDaqing163318China Toutai Oilfield Daqing Oil Field Co.Daqing163000China Natural Gas Branch the Third Group of Oil and Gas ProcessingDaqing Oil Field Co.Daqing163453China Mathematics and Statistics College Northeast Petroleum UniversityDaqing163318China

The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal *** flexible drilling tool is different from the conventional drilling *** flexible drilling pipe involves a mutual transition between the structure and the mechanism during the deformation *** the same time,the flexible drilling pipe and the eccentric guide tube,the guide tube and the wellbore generate random *** this paper,3-D beam elements,universal joint elements,rigid beam elements and the beam-beam contact elements are combined to establish a two-layer contact nonlinear finite element model of the flexible drilling tool in the *** dynamic relaxation method is introduced for numerical *** feasibility of the model and the algorithm is verified by an *** mechanical analysis of flexible drilling tool under the four hole inclinations in the oblique section is carried *** is found that the flexible drilling pipe has a“folded line”*** contact force between the flexible drilling pipe and the guide tube is randomly *** contact force between the guide tube and the wellbore in the oblique section is greater than that in the vertical *** the hole inclinations increase,the torque and axial force transmitted to the drill bit gradually decrease.

关键词： Flexible drilling tool beam element universal joint contact nonlinear finite element.