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Microsatellites reveal strong genetic structure in the common cutworm, Spodoptera litura

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Journal of Integrative Agriculture 2019年第3期18卷 636-643页

作者： WU Huai-heng wan Peng HUANG min-song LEI chao-liang Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory Huazhong Agricultural University Key Laboratory of Integrated Pest Management on Crops in Central China Institute of Plant Protection and Soil ScienceHubei Academy of Agricultural Sciences

The common cutworm, Spodoptera litura(Lepidoptera: Noctuidae), is a voracious agricultural pest. To increase understanding of the migration patterns and genetic diversity of different geographic populations of this species, we analyzed genetic variation in nine microsatellite loci among 576 individuals collected from 17 locations in China and one in Myanmar during 2011–2012. We successfully identified 162 alleles, with an average of 18 alleles per locus and a range of 5 to 34. The mean observed heterozygosity of the 18 populations ranged from 0.18 to 0.98, and the expected heterozygosity ranged from 0.19 to 0.89. For the nine microsatellite markers studied, polymorphism information content ranged from 0.18 to 0.88(mean=0.64). We found low genetic differentiation among the 18 populations(mean F-statistics(F_(ST))=0.05) and high genetic diversity among individuals. Principle coordinates analysis indicated no significant correlation between geographic and genetic distance(r=0.04). The value of N_m(N_m>4) estimated using coalescent-based methods suggests strong gene flow with migration. The nine microsatellite markers identified in this study will be beneficial for further investigation of migration patterns and genetic diversity in S. litura.

关键词： Spodoptera litura microsatellite genetic diversity

APPLICATION OF MAXIMUM ENTROPY PRINCIPLE METHOD TO THE STUDY OF WAVE CLIMATE STATISTICAL CHARACTERISTICS

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Journal of Hydrodynamics 2004年第4期16卷 417-422页

作者： XUFu-min XUEHong-chao CollegeofTrafficandOceanEngineering HohaiUniversityNanjing210098China

The Maximum Entropy Principle (MEP) method is elaborated, and thecorresponding probability density evaluation method for the random fluctuation system is introduced,the goal of the article is to find the best fitting method for the wave climate statisticaldistribution. For the first time, a kind of new maximum entropy probability distribution (MEPdistribution) expression is deduced in accordance with the second order moment of a random *** from all the fitting methods in the past, the MEP distribution can describe theprobability distribution of any random fluctuation system conveniently and reasonably. If themoments of the random signal is limited to the second order, that is, the ratio of theroot-mean-square value to the mean value of the random variable is obtained from the random sample,the corresponding MEP distribution can be computed according to the deduced expression in thisessay. The concept of the wave climate is introduced here, and the MEP distribution is applied tofit the probability density distributions of the significant wave height and spectral peak *** the Mexico Gulf as an example, three stations at different locations, depths and wind wavestrengths are chosen in the half-closed gulf, the significant wave height and spectral peak perioddistributions at each station are fitted with the MEP distribution, the Weibull distribution and theLog-normal distribution respectively, the fitted results are compared with the field observations,the results show that the MEP distribution is the best fitting method, and the Weibull distributionis the worst one when applied to the significant wave height and spectral peak period distributionsat different locations, water depths and wind wave strengths in the Gulf. The conclusion shows thefeasibility and reasonability of fitting wave climate statistical distributions with the deduced MEPdistributions in this essay, and furthermore proves the great potential of MEP method to the studyof wave sta

关键词： maximum entropy principle wave climate significant wave height spectralpeak period

Model reduction for supersonic cavity flow using proper orthogonal decomposition(POD)and Galerkin projection

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Applied Mathematics and Mechanics(English Edition) 2017年第5期38卷 723-736页

作者： chao ZHANG Zhenhua wan Dejun SUN Department of Modern Mechanics University of Science and Technology of ChinaHefei 230027China

The reduced-order model （ROM） for the two-dimensional supersonic cavity flow based on proper orthogonal decomposition （POD） and Galerkin projection is investigated. Presently, popular ROMs in cavity flows are based on an isentropic assumption, valid only for flows at low or moderate Mach numbers. A new ROM is constructed involving primitive variables of the fully compressible Navier-Stokes （N-S） equations, which is suitable for flows at high Mach numbers. Compared with the direct numerical simulation （DNS） results, the proposed model predicts flow dynamics （e.g., dominant frequency and amplitude） accurately for supersonic cavity flows, and is robust. The comparison between the present transient flow fields and those of the DNS shows that the proposed ROM can capture self-sustained oscillations of a shear layer. In addition, the present model reduction method can be easily extended to other supersonic flows.

关键词： supersonic cavity flow reduced-order model (ROM) proper orthogonal decomposition (POD) Galerkin projection

Mode transition and oscillation suppression in supersonic cavity flow

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Applied Mathematics and Mechanics(English Edition) 2016年第7期37卷 941-956页

作者： chao ZHANG Zhenhua wan Dejun SUN Department of Modern Mechanics University of Science and Technology of China

Supersonic flows past two-dimensional cavities with/without control are investigated by the direct numerical simulation （DNS）. For an uncontrolled cavity, as the thickness of the boundary layer declines, transition of the dominant mode from the steady mode to the Rossiter Ⅱ mode and then to the Rossiter III mode is observed due to the change of vortex-corner interactions. Meanwhile, a low frequency mode appears. However, the wake mode observed in a subsonic cavity flow is absent in the current simulation. The oscillation frequencies obtained from a global dynamic mode decomposition （DMD） approach are consistent with the local power spectral density （PSD） analysis. The dominant mode transition is clearly shown by the dynamic modes obtained from the DMD. A passive control technique of substituting the cavity trailing edge with a quarter-circle is studied. As the effective cavity length increases, the dominant mode transition from the Rossiter Ⅱ mode to the Rossiter Ⅲ mode occurs. With the control, the pressure oscillations are reduced significantly. The interaction of the shear layer and the recirculation zone is greatly weakened, combined with weaker shear layer instability, responsible for the suppression of pressure oscillations. Moreover, active control using steady subsonic mass injection upstream of a cavity leading edge can stabilize the flow.

关键词： supersonic cavity flow pressure oscillation mode transition vortex-corner interaction

A REVIEW ON RESEARCH ON DEVELOPMENT OF LIGAMENT CONSTITUTIVE RELATIONS ON MACRO, MESO, AND MICRO LEVELS

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Acta Mechanica Solida Sinica 2013年第4期26卷 331-343页

作者： chao wan Zhixiu Hao Shizhu Wen State Key Laboratory of Tribology Tsinghua University

Ligaments are densely connective soft tissues capable of maintaining stability and function of knee *** an important factor,the constitutive relation of ligament would affect its biomechanics and further play an essential role in the research on ligament injury,healing and *** objective of this paper is to provide an overview of the current research on ligament constitutive relations on the macro,meso,and micro levels as well as the anatomy and histological structure of *** studies of biomechanical behaviors during ligament injury and healing periods have also been *** on the research on ligament constitutive relation in the past three decades,a discussion of some research perspectives is also presented,such as a validated accurate measuring method of in situ strain in ligament,a new constitutive relation involving the distribution of ultra-structural properties,and a rational estimation of ligament injury and healing process by the change of its ultra-structural or histological characteristics.

关键词： constitutive relation ligament ultra-structure macro meso micro

Time-domain nonlinear aeroelastic analysis and wind tunnel test of a flexible wing using strain-based beam formulation

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Chinese Journal of Aeronautics 2021年第1期34卷 380-396页

作者： Yang MENG Zhiqiang wan Changchuan XIE chao AN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

A theoretical formulation for time-domain nonlinear aeroelastic analysis of a flexible wing model is presented and validated by wind tunnel tests. A strain-based beam model for nonlinear structural analysis is combined with the Unsteady Vortex Lattice Method(UVLM) to form the complete framework for aeroelastic analysis. The nonlinear second-order differential equations are solved by an implicit time integration scheme that incorporates a Newton-Raphson sub-iteration technique. An advanced fiber optic sensing technique is firstly used in a wind tunnel for measuring large structural deformations. In the theoretical study, the nonlinear flutter boundary is determined by analyzing the transient response about the nonlinear static equilibrium with a series of flow velocities. The gust responses of the wing model at various gust frequencies are also studied. Comparisons of the theoretical and experimental results show that the proposed method is suitable for determining the nonlinear flutter boundary and simulating the gust response of flexible wings in the time domain.

关键词： Flexible wings Flutter Geometric nonlinearity Gust response Wind tunnel test

The Linear Unicyclic Hypergraph with the Second or Third Largest Spectral Radius

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Acta Mathematica Sinica,English Series 2020年第10期36卷 1140-1150页

作者： chao DING Yi Zheng FAN Jiang chao wan School of Mathematics and Physics Anqing Normal UniversityAnqing 246133P.R.China School of Mathematical Sciences Anhui UniversityHefei 230601P.R.China

The spectral radius of a uniform hypergraph is defined to be that of the adjacency tensor of the *** is known that the unique unicyclic hypergraph with the largest spectral radius is a nonlinear hypergraph,and the unique linear unicyclic hypergraph with the largest spectral radius is a power *** this paper we determine the unique linear unicyclic hypergraph with the second or third largest spectral radius,where the former hypergraph is a power hypergraph and the latter hypergraph is a non-power hypergraph.

关键词： Linear unicyclic hypergraph adjacency tensor spectral radius weighted incident matrix

Modified constitutive models for Inconel 718 considering current density and temperature in electrically assisted forming process

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Chinese Journal of Aeronautics 2024年第2期37卷 524-540页

作者： Xuan CUI Rui ZHAO min wan School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

Electrically Assisted Forming(EAF)technology has obvious advantages in material *** develop an effective constitutive model considering electrical effects,room temperature and electrically assisted quasi-static uniaxial tensile tests were conducted using ultrathin nickelbased superalloy plates with a thickness of 0.25 *** research focused on the two most widely recognized effects:the Joule thermal and the electric athermal *** mechanism of current action can be divided into two scenarios:one considering the Joule thermal effect only,and the other considering both effects *** basic constitutive models,namely the Modified-Hollomon model and the Johnson-Cook(J-C)model,were selected to be optimized through the classification of two different situations,and four optimized constitutive models were *** was found that the J-C model with simultaneous consideration of the Joule thermal effect and electric athermal effect had the best prediction effect by comparing the results of these four ***,the accuracy of the optimization model was verified by finite element simulation of the electrically assisted stretching optimization *** results show that the constitutive model can effectively predict the temperature effect caused by the Joule heat effect and the athermal effect of current on the material.

关键词： Joule heating Elastoplasticity Plastic deformation Superalloys Constitutive models

Pre-compensation of Friction for CNC Machine Tools through Constructing a Nonlinear Model Predictive Scheme

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Chinese Journal of Mechanical Engineering 2023年第5期36卷 62-76页

作者： Qunbao Xiao min wan Xuebin Qin State IJR Center of Aerospace Design and Additive Manufacturing School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

Nonlinear friction is a dominant factor afecting the control accuracy of CNC machine *** paper proposes a friction pre-compensation method for CNC machine tools through constructing a nonlinear model predictive *** nonlinear friction-induced tracking error is frstly modeled and then utilized to establish the nonlinear model predictive scheme,which is subsequently used to optimize the compensation signal by treating the friction-induced tracking error as the optimization *** the optimization procedure,the derivative of compensation signal is constrained to avoid vibration of machine *** contrast to other existing approaches,the proposed method only needs the parameters of Stribeck friction model and an additional tuning parameter,while fnely identifying the parameters related to the pre-sliding phenomenon is not *** a result,it greatly facilitates the practical *** air cutting and real cutting experiments conducted on an in-house developed open-architecture CNC machine tool prove that the proposed method can reduce the tracking errors by more than 56%,and reduce the contour errors by more than 50%.

关键词： Nonlinear model predictive control Friction compensation P-PI controller Stribeck model