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Active control of multiscale features in wall-bounded turbulence

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Acta Mechanica Sinica 2020年第1期36卷 12-21页

作者： Xiaotong Cui nan jiang Xiaobo Zheng Zhanqi Tang Department of Mechanics Tianjin UniversityTianjin300354China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin300354China School of Naval Architecture Ocean&Civil Engineering Shanghai Jiao Tong UniversityShanghai200240China

This study experimentally investigates the impact of a single piezoelectric(PZT)actuator on a turbulent boundary layer from a statistical *** working conditions of the actuator include a range of frequencies and *** streamwise velocity signals in the turbulent boundary layer flow are measured downstream of the actuator using a hot-wire *** mean velocity profiles and other basic parameters are *** results obtained by discrete wavelet decomposition indicate that the PZT vibration primarily influences the near-wall *** turbulent intensities at different scales suggest that the actuator redistributes the near-wall turbulent *** skewness and flatness distributions show that the actuator effectively alters the sweep events and reduces intermittency at smaller ***,under the impact of the PZT actuator,the symmetry of vibration scales’velocity signals is promoted and the structural composition appears in an orderly *** distribution function results indicate that perturbation causes the fluctuations in vibration scales and smaller scales with high intensity and low *** on the flatness factor,the bursting process is also *** vibrations reduce the relative intensities of the burst events,indicating that the streamwise vortices in the buffer layer experience direct interference due to the PZT control.

关键词： Turbulent boundary layer Piezoelectric actuator Drag reduction Discrete wavelet decomposition Bursting process

Dynamic Hypergraph Modeling and Robustness Analysis for SIoT

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 3017-3034页

作者： Yue Wan nan jiang Ziyu Liu School of Information Engineering East China Jiaotong UniversityNanchang330013China

The Social Internet of Things(SIoT)integrates the Internet of Things(IoT)and social networks,taking into account the social attributes of objects and diversifying the relationship between humans and objects,which overcomes the limitations of the IoT’s focus on associations between *** Intelligence(AI)technology is rapidly *** is critical to build trustworthy and transparent systems,especially with system security issues coming to the *** paper emphasizes the social attributes of objects and uses hypergraphs to model the diverse entities and relationships in SIoT,aiming to build an SIoT hypergraph generation model to explore the complex interactions between entities in the context of intelligent *** hypergraph generation models impose too many constraints and fail to capture more details of real *** contrast,this paper proposes a hypergraph generation model that evolves dynamically over time,where only the number of nodes is *** combines node wandering with a forest fire model and uses two different methods to control the size of the *** new nodes are added,the model can promptly reflect changes in entities and relationships within *** results exhibit that our model can effectively replicate the topological structure of real-world *** also evaluate the vulnerability of the hypergraph under different attack strategies,which provides theoretical support for building a more robust intelligent SIoT hypergraph model and lays the foundation for building safer and more reliable systems in the future.

关键词： Large-scale artificial intelligence Social Internet of Things hypernetwork robustness analysis

Theoretical study of interactions between human adult hemoglobin and acetate ion by polarizable force field and fragmentation quantum chemistry methods

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Science China Chemistry 2009年第11期52卷 1925-1931页

作者： YAN XiuFen jiang nan MA jing School of Chemistry and Chemical Engineering Institute of Theoretical and Computational ChemistryKey Laboratory of Mesoscopic Chemistry of MOENanjing UniversityNanjing 210093China

A series of theoretical approaches,including conventional FF03 and FF03-based polarization model,as well as the generalized energy-based fragmentation(GEBF) quantum chemistry method,have been applied to investigate the interactions between acetate ion(CH3COO-) and the α-subunit of human adult hemoglobin(designated as Hb-α) at four binding sites(Lys16,Lys90,Arg92,and Lys127),*** FF03-based polarizable force fields show that the interaction energies between the CH3COO-group and Hb-α follow the trend of Arg92>Lys127>Lys90>*** complexation of CH3COO-with Hb-α is governed by the long-range electrostatic interactions and steric effect.

关键词： polarization model fragmentation QM method hemoglobin interaction

Modelling the ZR Relationship of Precipitation Nowcasting Based on Deep Learning

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Computers, Materials & Continua 2022年第7期72卷 1939-1949页

作者： jianbing Ma Xianghao Cui nan jiang Chengdu University of Information Technology Chengdu610225China Bournemouth University BournemouthBH125BBUK

Sudden precipitations may bring troubles or even huge harm to people’s daily *** a timely and accurate precipitation nowcasting is expected to be an indispensable part of our modern ***,the rainfall intensity estimation from weather radar is based on the relationship between radar reflectivity factor(Z)and rainfall rate(R),which is typically estimated by location-dependent experiential formula and arguably ***,in this paper,we propose a deep learning-based method to model the ZR *** evaluate,we conducted our experiment with the Shenzhen precipitation *** proposed a combined method of deep learning and the ZR relationship,and compared it with a traditional ZR equation,a ZR equation with its parameters estimated by the least square method,and a pure deep learning *** experimental results show that our combined model performsmuch better than the equation-based ZRformula and has the similar performance with a pure deep learning nowcasting model,both for all level precipitation and heavy ones only.

关键词： Deep learning meteorology precipitation nowcasting weather forecasting ZR formula

Thermally controlled large deformation in temperaturesensitive hydrogels bilayers

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International Journal of Smart and nano Materials 2021年第4期12卷 450-471页

作者： jianying Hu nan jiang jianke Du Department of Mechanics and Engineering Science Smart Materials and Advanced Structure LaboratorySchool of Mechanical Engineering and MechanicsNingbo UniversityNingboChina State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’anChina

The present work investigates the thermally controlled deformation characteristics in temperature-sensitive hydrogels *** free energy density for temperature-sensitive hydrogels is modified,upon which the finite element model is developed and implemented through user-defined material subroutine UHYPER in the commercial software *** modified UHYPER implementation allows for more vividly depicting the continuous deformation in phase temperature region for temperature-sensitive *** thermally controlled cases of temperature-sensitive hydrogel including grippers,self-folding boxes,thermally driven origami are presented to illustrate a wide array of complex interesting applications or ***,we develop a simple model to theoretically calculate the bending angle of the temperature-sensitive hydrogel bilayers,which has been validated by the finite element simulation *** study can provide more insights for optimal design in thermally controlled hydrogels structures.

关键词： Temperature-sensitive hydrogels thermally controlled deformation swelling-induced bending

An improved adaptive Sage filter with applications in GEO orbit determination and GPS kinematic positioning

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Science China(Physics,Mechanics & Astronomy) 2012年第5期55卷 892-898页

作者： XU TianHe jiang nan SUN ZhangZhen Xi'an Research Institute of Surveying and Mapping Xi'an 710054China GFZ German Research Centre for Geosciences Potsdam 14473Germany College of Geology Engineering and Geomatic Chang'an UniversityXi'an 710054China

The shortcomings of an adaptive Sage filter are analyzed in this *** improved adaptive Sage filter is developed by using a weighted average quadratic form of the historical residuals of observations and predicted states to evaluate the covariance matrices of observations and dynamic model errors at the present *** weight function is constructed based on the variances of observational residuals or predicted state residuals and the space distance between the previous and the present *** order to balance the contributions of the measurements and the dynamic model information,an adaptive factor is applied by using a two-segment function and predicted state discrepancy *** applications,orbit determination of a maneuvered GEO satellite and GPS kinematic positioning,are conducted to verify the performance of the proposed method.

关键词： Kalman filter adaptive Sage filter orbit determination kinematic positioning two-segment function

THE(U+K)-ORBITS OF ESSENTIALLY NORMAL OPERATORS AND THEIR STRONG IRREDUCIBILITY

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Chinese Annals of Mathematics,Series B 1998年第2期19卷 217-228页

作者： ji YOUQING jiang CHUNLAN jilin Univ Inst Math Changchun 130023 Peoples R China

The authors characterize the (U+K) orbits of a class essentially normal operators and prove that some essentially normal operators with connected spectrum are strongly irreducible after a small compact perturbation.... 详细信息

关键词： Strongly irreducible operator Compact perturbation Normal operator

New specimens of Stenocybus acidentatus(Therapsida: Dinocephalia) from the Middle Permian Dashankou Fauna of China

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Acta Geologica Sinica(English Edition) 2014年第3期88卷 730-737页

作者： jiang Shan ji Shu-an Institute of Geology Chinese Academy of Geological Sciences Key Laboratory of Stratigraphy and Paleontology Ministry of Land and Resources

The basal dinocephalian clade Stenocybusidae was known from two incomplete specimens representing one generus,Stenocybus,from Dashankou fanua in Yumen,Gansu Province of *** holotype of Stenocybus acidentatus is laterally compressed,making some characters *** we describe two new specimens of Stenocybus acidentatus from the same locality,an anterior portion of skull with articulated jaws,and a right dentary with nearly complete *** show some detailed features on the morphology of the premaxilla,maxilla,nasal,external nares and *** phylogenetic relationship between Stenocybus acidentatus and the relatively large Sinophoneus yumenensis is still difficult to determine,and needs more new complete material and further evidences.

关键词： Dinocephalia Stenocybusidae Dashankou Fauna Middle Permian

Experimental investigation of Reynolds stress complex eddy viscosity model for coherent structure dynamics

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Science China(Physics,Mechanics & Astronomy) 2011年第7期54卷 1319-1327页

作者： jiA YongXia TANG ZhanQi jiang nan State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Mechanics School of Mechanical Engineering Tianjin University Tianjin 300072 China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin 300072 China

Time sequence signals of streamwise and normal velocity components,as well as velocity strain rate,at different vertical locations in the turbulent boundary layer over a smooth flat plate in a wind tunnel have been finely examined by the use of double-sensor hot-wire *** local module maximum for wavelet coefficient of longitudinal velocity component,as a detecting index,is employed to educe the ejection and sweep process of the coherent structure burst in the turbulent boundary layer from the random fluctuating *** coherent waveforms of Reynolds stress residual contribution term for random fluctuations to coherent structure,as well as the velocity strain rate of coherent structure,are extracted by the conditional phase average *** on the theoretical analysis of eddy viscosity coefficient in complex eddy viscosity model for coherent structure,the macro-relaxation effect between Reynolds stress residual contribution term of random fluctuations to coherent structure and the velocity strain rate of coherent structure is studied and the variations of the phase difference between them across the turbulent boundary layer are investigated *** rationality of complex eddy viscosity model for coherent structure is confirmed through the investigation.

关键词： turbulent boundary layer coherent structure complex eddy viscosity model Reynolds stress phase difference