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Relative Time-Restricted Sensitivity and Entropy

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Communications in Mathematics and Statistics 2024年第2期12卷 265-277页

作者： xiaochen wang Xiaomin Zhou Department of Mathematics University of Science and Technology of ChinaHefei 230026AnhuiPeople’s Republic of China School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China

In this paper,we consider relativization of measure-theoretical-restricted *** a given topological dynamical system,we deﬁne conditional measure-theoretical-restricted asymptotic rate with respect to sensitivity and obtain that it equals to the reciprocal of the Brin–Katok local entropy for almost every point under the conditional measure.

关键词： Relative time-restricted sensitivity Asymptotic rate Local entropy

Experimental investigation into the oxidation reactivity,morphology and graphitization of soot particles from diesel/n-octanol mixtures

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Journal of Environmental Sciences 2022年第2期34卷 218-230页

作者： Qiongyang Zhou Ying wang xiaochen wang Yuanqi Bai School of Energy and Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity,morphology and graphitization of diesel exhaust particles,soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100(neat diesel fuel),DO15(85%diesel and 15%n-octanol,V/V)and DO30(70%diesel and 30%n-octanol,V/V).All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N·*** soot properties were characterized by thermogravimetric analyzer(TGA),transmission electron microscopy(TEM)and Raman spectroscopy(RS).The higher volatile organic fraction content,lower soot oxidation temperatures and lower activation energy from TGA results indicated that both the increasing n-octanol concentration and engine speed enhanced the soot oxidation ***,quantitative analysis of TEM images showed that the soot derived from DO30 had the smallest primary particle diameters and fractal dimension,followed by those of soot produced by DO15 and *** RS results demonstrated that the n-octanol addition and higher engine speed led to a larger D1-FWHM(D1-full width at half maximum),A_(D1)/A_(T)(area ratio of D1 band and the total spectral)and A_(D3)/A_(T)(area ratio of D3 band and the total spectral)as well as a smaller L_(a)(crystallite width),revealing a lower degree of ***,the correlations between characterization parameters of soot properties and reactivity were nonlinear.

关键词： Oxidation reactivity Morphology Graphitization Diesel exhaust particles n-Octanol

Control Design for Harmonic Disturbance Rejection for Robot Manipulators with Bounded Inputs

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 248-256页

作者： YAO Yu wang xiaochen HE Fenghua Control and Simulation Center Harbin Institute of Technology Harbin 150080 China

Currently most of control methods are of one degree of freedom（1-DOF） control structure for the robot systems which are affected by unmeasurable harmonic disturbances,at the same time in order to obtain perfect disturbance attenuation level,the controller gain must be *** practice,however,for robotic actuators,there are physical constraints that limit the amplitude of the available *** paper considers the problem of tracking control under input constraints for robot manipulators which are affected by unmeasurable harmonic disturbances.A new control scheme is proposed for the problem,which is composed of a parameter-dependent nonlinear observer and a tracking *** parameter-dependent nonlinear observer,designed based on the internal model principle,can achieve an estimation and compensation of a class of harmonic disturbances with unknown *** tracking controller,designed via adaptive control techniques,can make the systems asymptotically track the desired *** the control design,the continuous piecewise differentiable increasing function is used to limit control input amplitude,such that the control input saturation is *** Lyapunov stability of closed loop systems is *** validate proposed control scheme,simulation results are provided for a two link horizontal robot *** simulation results show that the proposed control scheme ensures asymptotic tracking in presence of an uncertain external disturbance acting on the *** important feature of the methodology consists of the fact that the designed controller is of 2-DOF control structure,namely,it has the ability to overcome the conflict between controller gain and robustness against external disturbances in the traditional 1 -DOF control structure framework.

关键词： tracking control of robot harmonic disturbance rejection internal model principle input constraint adaptive control

Aeroelastic stability analysis of heated flexible panel subjected to an oblique shock

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Chinese Journal of Aeronautics 2018年第8期31卷 1650-1666页

作者： Liuqing YE Zhengyin YE xiaochen wang School of Aeronautics Northwestern Polytechnical University Xi'an 710072 China

The critical conditions for aeroelastic stability and the stability boundaries of a flexible two-dimensional heated panel subjected to an impinging oblique shock are considered using theoretical analysis and numerical computations, respectively. The von-Karman large deflection theory of isotropic flat plates is used to account for the geometrical nonlinearity of the heated panel, and local first-order piston theory is employed in the region before and after shock waves to estimate the aerodynamic pressure. The coupled partial differential governing equations, according to the Hamilton principle, are established with thermal effect based on quasi-steady thermal stress *** Galerkin discrete method is employed to truncate the partial differential equations into a set of ordinary differential equations, which are then solved by the fourth-order Runge-Kutta numerical integration method. Lyapunov indirect method is applied to evaluate the stability of the heated panel. The results show that a new aeroelastic instability（distinct from regular panel flutter） arises from the complex interaction of the incident and reflected wave system with the panel flexural modes and thermal loads. What＇s more, stability of the panel is reduced in the presence of the oblique shock. In other words, the heated panel becomes aeroelastically unstable at relatively small flight aerodynamic pressure.

关键词： AerothermoelasticityHeated panel Local piston theory Shock waves Stability Thermal flutter

Visible-light-mediated tungsten-catalyzed C-H amination of unactivated alkanes with nitroarenes

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Science China Chemistry 2022年第4期65卷 678-685页

作者： Qing wang Shengyang Ni xiaochen wang Yi wang Yi Pan State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Alkylamines are important motifs in pharmaceutical and material *** existing reports of C-H amination are limited to ammonia,diazo and azide nitrogen *** work describes a rapid construction of C-N bonds from accessible nitroarene and alkane feedstock under decatungstate catalysis.A variety of C-H precursors including gaseous,linear,cyclic and benzylic hydrocarbons could adopt this protocol to afford the corresponding alkylamines in high efficiency.

关键词： amination photoredox light alkane nitrobenzene

Aeroelastic effect on aerothermoacoustic response of metallic panels in supersonic flow

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Chinese Journal of Aeronautics 2016年第6期29卷 1635-1648页

作者： wang xiaochen Yang Zhichun Zhou Jian Hu Wei School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Xi’an Aerospace Propulsion Institute Xi’an 710100China

A finite element formulation is presented for the analysis of the aeroelastic effect on the aerothermoacoustic response of metallic panels in supersonic flow. The first-order shear deformation theory(FSDT) and the von Karman nonlinear strain-displacement relationships are employed to consider the geometric nonlinearity induced by large deflections. The piston theory and the Gaussian white noise are used to simulate the mean flow aerodynamics and the turbulence from the boundary layer. The thermal loading is assumed to be steady and uniformly distributed, and the material properties are assumed to be temperature independent. The governing equations of motion are firstly formulated in structural node degrees of freedom by using the principle of virtual work,and then transformed and reduced to a set of coupled nonlinear Duffing oscillators in modal coordinates. The dynamic response of a panel is obtained by the Runge-Kutta integration method. The results indicate that the increasing aeroelastic effect can lead the panel vibration from a random motion to a highly ordered motion in the fashion of diffused limit cycle oscillations(LCOs), and remarkably alter the stochastic bifurcation and the spectrum of the aerothermoacoustic *** the other hand there exists a counterbalance mechanism between the external random loading and the aeroelastic effect, which mainly functions through the nonlinear frequency-amplitude response. It is surmised that the aeroelastic effect must be considered in sonic fatigue analysis for panel structures in supersonic flow.

关键词： Aeroelastic effect Aerothermoacoustic response Metallic panels Nonlinear frequencyamplitude response Sonic fatigue

Retrieval of Significant Wave Height Under Typhoon Conditions from Gaofen-3 SAR Imagery

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Journal of Ocean University of China 2022年第1期21卷 81-90页

作者： wang xiaochen HAN Bing ZHONG Lihua YUAN Xinzhe Aerospace Information Research Institute Chinese Academy of ScienceBeijing 100190China Key Laboratory of Technology in Geo-Spatial Information Processing and Application Systems Aerospace Information Research InstituteChinese Academy of ScienceBeijing 100190China The National Satellite Ocean Applications Center Beijing 100081China

The objective of this paper is to propose an empirical method to inverse significant wave height(SWH)under typhoon conditions from collected dual-polarization Gaofen(GF)-3 synthetic aperture radar(SAR)*** typhoon scenes were cap-tured from narrow scan(NSC)and wide scan(WSC)images,and collocated with European Center for Medium-Range Weather Fore-casts reanalysis data of(ECMWF).To improve the quality of GF-3 SAR images,the recalibration over rainforest and de-scalloping were carried *** establish the empirical relationship between SAR-derived parameters and collocated SWH,the sensitivity analysis of typical parameters about the normalized radar cross section(Nrcs)and imagery variance(Cvar)were performed to both VV and VH polarized *** scenes from GF-3 SAR imagery under typhoon conditions were used for training the model by the multivari-ate least square regression,and one scene was used for preliminary *** was found that the joint retrieval model based on VV and VH polarized SAR imagery performed better than any single polarized *** results,verified by using ECMWF data,revealed the soundness of this approach,with a correlation of 0.95,bias of 0 m,RMSE of 0.44 and SI of 0.01 when VV polarization and VH polarization data were both used.

关键词： Gaofen-3 SAR typhoon significant wave height

Two diversities meet in the rhizosphere:root specialized metabolites and microbiome

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Journal of Genetics and Genomics 2024年第5期51卷 467-478页

作者： xiaochen wang Jingying Zhang Xinjun Lu Yang Bai Guodong wang State Key Laboratory of Plant Genomics Institute of Genetics and Developmental BiologyThe Innovative Academy of Seed DesignChinese Academy of SciencesBeijing 100101China CAS-JIC Centre of Excellence for Plant and Microbial Science Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China Hainan Yazhou Bay Seed Laboratory SanyaHainan 572025China College of Advanced Agricultural Sciences Chinese Academy of SciencesBeijing 100049China

Plants serve as rich repositories of diverse chemical compounds collectively referred to as specialized *** compounds are of importance for adaptive processes,including interactions with various microbes both beneficial and *** microbes as bioreactors,the chemical diversity undergoes dynamic changes when root-derived specialized metabolites(RSMs)and microbes encounter each other in the *** advancements in sequencing techniques and molecular biology tools have not only accelerated the elucidation of biosynthetic pathways of RSMs but also unveiled the significance of RSMs in plant-microbe *** this review,we provide a comprehensive description of the effects of RSMs on microbe assembly in the rhizosphere and the influence of corresponding microbial changes on plant health,incorporating the most up-to-date information ***,we highlight open questions that remain for a deeper understanding of and harnessing the potential of RSM-microbe interactions to enhance plant adaptation to the ***,we propose a pipeline for investigating the intricate associations between root exometabolites and the rhizomicrobiome.

关键词： Root specialized metabolites Microbiome Plant-microbe interactions Rhizosphere Diversity

High Quality Audio Object Coding Framework Based on Non-Negative Matrix Factorization

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China Communications 2017年第9期14卷 32-41页

作者： Tingzhao Wu Ruimin Hu xiaochen wang Shanfa Ke Jinshan wang National Engineering Research Center for Multimedia Software School of Computer ScienceWuhan University Hubei Key Laboratory of Multimedia and Network Communication Engineering Wuhan University Collaborative Innovation Center of Geospatial Technology

Object-based audio coding is the main technique of audio scene coding. It can effectively reconstruct each object trajectory, besides provide sufficient flexibility for personalized audio scene reconstruction. So more and more attentions have been paid to the object-based audio coding. However, existing object-based techniques have poor sound quality because of low parameter frequency domain resolution. In order to achieve high quality audio object coding, we propose a new coding framework with introducing the non-negative matrix factorization(NMF) method. We extract object parameters with high resolution to improve sound quality, and apply NMF method to parameter coding to reduce the high bitrate caused by high resolution. And the experimental results have shown that the proposed framework can improve the coding quality by 25%, so it can provide a better solution to encode audio scene in a more flexible and higher quality way.

关键词： object-based audio coding non-negative matrix factorization audio scenecoding