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Precise drag prediction of airfoil flows by a new algebraic model

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Acta Mechanica Sinica 2020年第1期36卷 35-43页

作者： Meng-juan xiao Zhen-Su She State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking UniversityBeijing100871China

We report the results of accurate prediction of lift(C L)and drag(C D)coefficients of two typical airfoil flows(NACA0012 and RAE2822)by a new algebraic turbulence model,in which the eddy viscosity is specified by a stress length(SL)function predicted by structural ensemble dynamics(SED)*** accuracy of the prediction of C D with error of a few counts(one count is 10−4)and of C L with error under 1%-2%are uniformly obtained for varying angles of attack(AoA),indicating an order of magnitude improvement of drag prediction accuracy compared to currently used models(typically around 20 to 30 counts).More interestingly,the SED-SL model is distinguished with fewer parameters of clear physical meaning,which quantify underlying turbulent boundary layer(TBL)with a universal multi-layer structure,and is thus promising to be more easily generalizable to complex *** use of the new model for the calibration of flow condition in experiment and the extraction of flow physics from numerical simulation data of aeronautic flows are discussed.

关键词： Lift and drag coefficients Airfoil Flows Stress Length Structural ensemble dynamics

On the convergence for PNQD sequences with general moment conditions

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Applied Mathematics(A Journal of Chinese Universities) 2020年第2期35卷 184-192页

作者： xiao juan QIU De-hua School of Mathematics and Statistics Hengyang Normal UniversityHengyang 421008China School of Statistics and Mathematics Guangdong University of Finance and EconomicsGuangzhou 510320China

Let fX;Xn;n≥1g be a sequence of identically distributed pairwise negative quadrant dependent(PNQD)random variables and fan;n1g be a sequence of positive constants with an=f(n)and f(θ^k)=f(θ^k-1)for all large positive integers k,where 10(x≥1)is a non-decreasing function on[b;+1)for some b≥1:In this paper,we obtain the strong law of large numbers and complete convergence for the sequence fX;Xn;n≥1g,which are equivalent to the general moment conditionΣ∞n=1P(|X|>an)<*** results extend and improve the related known works in Baum and Katz[1],Chen at al.[3],and Sung[14].

关键词： pairwise negative quadrant dependent(PNQD)random variable strong law of large numbers complete convergence general moment condition

Symmetry-based description of laminar-turbulent transition

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Science China(Physics,Mechanics & Astronomy) 2019年第9期62卷 79-85页

作者： Meng-juan xiao Zhen-Su She Department of Mechanics and Engineering Science and State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking University

We report a simple but accurate description of flat plate transitional flow based on a structural ensemble dynamics(SED) theory of wall turbulence. It is postulated and verified by simulation data that a multi-layer stress length(SL) function ?12 presents a two-state structure in the streamwise x direction, characterizing the laminar-turbulent transition. The resulting algebraic model(called SED-SL) predicts correctly for the first time the entire streamwise profiles of the friction coefficient, Cf(x), of all seven sets of experimental(of e.g. T3 series) and simulations data of flat plate transitional flows, with varying incoming turbulence intensities Tu(or scales), superior to other closure models, with a two-state correlation for transition location Rex*= 3.3 × 10^6(1 +(Tu/0.65)^4)^-1.5/4. The extension to accurate description of transitional flows of engineering interests is discussed.

关键词： SED theory stress length multi-layer

数字经济背景下高校大数据与会计专业课程思政建设研究

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湖北科技学院学报 2025年第1期45卷 110-115页

作者：陈晓娟龚斌安咸宁职业技术学院湖北咸宁437100

在数字经济背景下,企业正面临着数字化转型,大数据与会计专业课程思政建设也需与时俱进。伴随新质生产力的发展,企业对财会人才的需求逐渐由核算向管理型转变,企业对财会人才的综合素养,也提出了更高的要求。本文将针对目前高校大数据... 详细信息

在数字经济背景下,企业正面临着数字化转型,大数据与会计专业课程思政建设也需与时俱进。伴随新质生产力的发展,企业对财会人才的需求逐渐由核算向管理型转变,企业对财会人才的综合素养,也提出了更高的要求。本文将针对目前高校大数据与会计专业课程思政建设中存在的对课程思政的认识与重视不够、思政元素挖掘与建设不深、思政元素融入与实践性不强等问题,提出以立德树人为根本任务,构建“一模式、三聚焦、三协同”的“一三三”思政育人体系,并探讨对应的建设保障机制,以期更好地推进数字经济背景下大数据与会计专业课程思政建设与发展。

关键词：数字经济大数据与会计课程思政

One-Dimensional Chain of n-Level Atoms and Discrete Nonlinear Schrödinger Equation

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Chinese Physics Letters 1999年第4期16卷 238-240页

作者： LIU xiao-juan xiao Yi HAI Wen-hua Department of Physics Xiangtan Normal CollegeXiangtan 411201 Department of Physics Huazhong University of Science and TechnologyWuhan 430074 Department of Physics Hu’nan Normal UniversityChangsha 410081

The Hamiltonian of one-dimensional chain of n-level atoms is represented in terms of Boson operators by using the Dyson-Maleev transformation and it is shown that the finite-ladder effect disappears when n tends toward *** this way,it is found that the Heisenberg equation of motion of this system is exactly described in the coherent state representation by the dark discrete nonlinear Schrödinger(DNLS)*** is also briefly shown that the DNLS equation has some general soliton *** indicates that this simple system has richness of nonlinear waves.

关键词： equation. system equation

Degree elevation of unified and extended spline curves

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第12期15卷 1098-1105页

作者： xiao-juan DUAN Guo-zhao WANG Department of Mathematics Zhejiang University

Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this paper is the degree elevation algorithm of UE-spline curves and its geometric meaning. Our main idea is to elevate the degree of UE-spline curves one knot interval by one knot interval. First, we construct a new class of basis functions, called bi-order UE-spline basis functions which are defined by the integral definition of *** some important properties of bi-order UE-splines are given, especially for the transformation formulae of the basis functions before and after inserting a knot into the knot vector. Finally, we prove that the degree elevation of UE-spline curves can be interpreted as a process of corner cutting on the control polygons, just as in the manner of B-splines. This degree elevation algorithm possesses strong geometric intuition.

关键词： Degree elevation Unified and extended splines(UE-splines) Bi-order UE-splines Corner cutting Geometric explanation

NUAT T-splines of odd bi-degree and local refinement

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Applied Mathematics(A Journal of Chinese Universities) 2014年第4期29卷 410-421页

作者： DUAN xiao-juan WANG Guo-zhao Department of Mathematics Zhejiang University

This paper presents a new kind of spline surfaces, named non-uniform algebraic- trigonometric T-spline surfaces （NUAT T-splines for short） of odd hi-degree. The NUAT T- spline surfaces are defined by applying the T-spline framework to the non-uniform algebraic- trigonometric B-spline surfaces （NUAT B-spline surfaces）. Based on the knot insertion algorithm of the NUAT B-splines, a local refinement algorithm for the NUAT T-splines is given. This algorithm guarantees that the resulting control grid is a T-mesh as the original one. Finally, we prove that, for any NUAT T-spline of odd hi-degree, the linear independence of its blending functions can be determined by computing the rank of the NUAT T-spline-to-NUAT B-spline transformation matrix.

关键词： odd bi-degree non-uniform algebraic-trigonometric T-spline local refinement blending function,linear independence.

Exact solutions for different vorticity functions of couple stress fluids

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第5期9卷 672-680页

作者： Saeed ISLAM Chao-ying ZHOU xiao-juan RAN Department of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen Graduate School Shenzhen 518055 China COMSATS Institute of lnformation Technology Islamabad 44000 Pakistan

In this paper, inverse solutions are obtained for the class of 2D steady incompressible couple stress fluid flows. This class consists of flows for which the vorticity distribution is given by ▽2ψ=ψ+f(x,y). The solutions are obtained by applying the inverse method, which makes certain hypotheses regarding the form of the velocity field and pressure but without making any regarding the boundaries of the domain occupied by the fluid. Inverse solutions are derived for three different forms of f(x,y).

关键词： Exact solutions Vorticity functions Beltrami flow Couple stress fluid

交联型聚乙烯醇纸张表面施胶剂的制备及其应用

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陕西科技大学学报 2025年第1期43卷 1-7页

作者：费贵强李实肖文娟杨晨榕解攀陕西科技大学化学与化工学院陕西省轻化工助剂重点实验室陕西西安710021 西安北方惠安化学工业有限公司陕西西安710302

为了改善聚乙烯醇、淀粉作为纸张表面施胶剂的应用性能,选用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)和硼砂(STB)为交联剂,交联改性淀粉(PS)和聚乙烯醇(PVA1799),制备出不同交联程度的纸张表面施胶剂(CPSn-PVA).通过傅里叶红外光谱(FT-I... 详细信息

为了改善聚乙烯醇、淀粉作为纸张表面施胶剂的应用性能,选用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)和硼砂(STB)为交联剂,交联改性淀粉(PS)和聚乙烯醇(PVA1799),制备出不同交联程度的纸张表面施胶剂(CPSn-PVA).通过傅里叶红外光谱(FT-IR),扫描电镜(SEM)及稳定性测试对纸张表面施胶剂的性能进行了表征,探讨了KH560和STB的添加比例对纸张施胶剂的性能以及施胶后纸张物理性能的影响.实验结果表明,当STB添加量为0.1 g、KH560添加量为3 g时,纸张施胶剂膜拉伸强度可达25.6 MPa、断裂伸长率为326%.同时,与原纸相比,多重交联型纸张表面施胶剂表现出良好的应用性能,施胶后的纸张耐折次数、撕裂指数、接触角分别提升了6700%、65.04%、89.7%.

关键词：表面施胶剂改性淀粉聚乙烯醇硅烷偶联剂稳定性耐折度