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A new simpler rotation/curvature correction method for Spalart-Allmaras turbulence model

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Chinese Journal of Aeronautics 2013年第2期26卷 326-333页

作者： Zhang Qiang yang yong National Key Laboratory of Science and Techniques on Aerodynamic Design and Research Northwestern Polytechnical University

A new and much simpler rotation and curvature effects factor, which takes the form of Richardson number suggested by Hellsten originally for SST k-ω model, is presented for Spalart and Shur＇s rotation and curvature correction in the context of Spalart-Allmaras （SA） turbulence model. The new factor excludes the Lagrangian derivative of the strain rate tensor that exists in the SARC model, resulting in a simple, efficient and easy-to-implement approach for SA turbulence model （denoted as SARCM） to account for the effects of system rotation and curvature, techniquely. And then the SARCM is tested through turbulent curved wall flows： one is the flow over a zeropressure-gradient curved wall and the other is the channel flow in a duct with a U-turn. Predictions of the SARCM model are compared with experimental data and with the results obtained using original SA and SARC models. The numerical results show that SARCM can predict the rotation-curvature effects as accurately as SARC, but considerably more efficiently. Additionally, the accuracy of SARCM might strongly depend on the rotation-curvature model constants. Suggesting values for those constants are given, after some trials and errors.

关键词： Accuracy Computation Curvature Improvement Robust Rotation Strain rate tensor Turbulence model

Adaptive perturb and observe maximum power point tracking with current predictive and decoupled power control for gridconnected photovoltaic inverters

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 422-432页

作者： yong yang Huiqing WEN School of Rail Transportation Soochow UniversitySuzhou 215137China Department of Electrical and Electronic Engineering Xi’an Jiaotong-Liverpool UniversitySuzhou 215123China

In order to improve maximum power point tracking(MPPT) performance, a variable and adaptive perturb and observe(P&O)method with current predictive control is proposed. This is applied in three-phase threelevel neutral-point clamped(NPC) photovoltaic(PV)generation systems. To control the active power and the reactive power independently,the decoupled power control combined with a space vector modulation block is adopted for three-phase NPC inverters in PV generation *** balance the neutral-point voltage of the three-phase NPC grid-connected inverter, a proportional and integral control is used by adj usting the dwell time of small voltage vectors. A three-phase NPC inverter rated at 12 kVA was established. The performance of the proposed method was tested and compared with the fixed perturbation MPPT algorithm under different conditions. Experimental results confirm the feasibility and advantages of the proposed method.

关键词： Maximum power point tracking(MPPT) Perturb and observe(P&O) Current predictive controlDecoupled power control Three-phase neutral-point clamped inverter

Hlder continuity for a class of X-elliptic equations with singular lower order term

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Applied Mathematics(A Journal of Chinese Universities) 2009年第1期24卷 56-64页

作者： JIN yong-yang Dept. of Appl. Math. Zhejiang Univ. of Tech. Hangzhou 310023 China

The regularity for a class of X-elliptic equations with lower order termLu＋vu=-∑i,j=1 mXj^＊（aij（x）Xiu）＋vu=μis studied, where X = {X1,..., Xm} is a family of locally Lipschitz continuous vector fields, v is in certain Morrey type space and μ a nonnegative Radon measure. The HSlder continuity of the solution is proved when μ satisfies suitable growth condition, and a converse result on the estimate of μ is obtained when u is in certain HSlder class.

关键词： X-elliptic operator Hlder continuity Morrey type space

Scattering of SH waves by a scalene triangular hill with a shallow cavity in half-space

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 877-897页

作者： Sun Yingchao yang Zailin yang yong Wang Guangyi College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China AVIC-HONGDU Nanchang 330024China Key Laboratory of Advanced Material of Ship and Mechanics Ministry of Industry and Information TechnologyHarbin Engineering UniversityHarbin 150001China Engineering Research Institute of Appraisal and Strengthening Shandong Jianzhu UniversityJinan 250101China Jiangxi Technology Innovation Center of Advanced Aviation Structure and System Integration Nanchang 330024China

In this study,a theoretical approach is used to investigate the scattering problem of circular holes under a scalene triangle on the *** wave displacement function is obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by adopting the method of separation of *** on the complex function,multi-polar coordinate method,and region-matching technique,algebraic equations are established at auxiliary boundaries and free boundaries conditions in a complex *** auxiliary circle is used to solve the singularity of the reflex angle at the triangle ***,according to sample statistics,the least squares method is used instead of the Fourier expansion method to solve the undetermined coefficient of the algebraic equations by discrete *** results show that the continuity of the auxiliary boundaries and the accuracy of the zero-stress boundaries are adequate,and the displacement of the free surface and the stress of the circular hole are related to the shape of the triangle,the position of the circular hole,the direction of the incident wave,and the frequency content of the ***,time-domain responses are calculated by FFT based on the frequency domain theory,and the results reveal the wave propagation mechanism in a complicated structure.

关键词： earthquake ground motions theoretical seismology wave scattering and diffraction wave propagation

Comments on National guidelines for diagnosis and treatment of prostate cancer 2022 in China (English version)

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Chinese Journal of Cancer Research 2022年第5期34卷 456-457页

作者： yong yang Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing) Department of UrologyPeking University Cancer Hospital&InstituteBeijing 100142China

National guidelines for diagnosis and treatment of prostate cancer 2022 in China (English version)(1) was organized by the National Health Commission of the People’s Republic of China, led by the Cancer Hospital of the Chinese Academy of Medical Sciences, and jointly compiled by well-known experts across China. On the basis of the 2018version, the 2022 version of the guideline not only absorbs the updated content of the latest international guidelines.

关键词： diagnosis cancer treatment

Dynamic Response of Tunnel Structures in Inhomogeneous Medium Under SHWave:Shear Modulus in Quadratic Functional Form

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Acta Mechanica Solida Sinica 2023年第3期36卷 457-468页

作者： Zailin yang Jinlai Bian Huanan Xu yong yang College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China School of Resource Engineering Longyan UniversityLongyan 364012China Key Laboratory of Advanced Material of Ship and Mechanics Ministry of Industry and Information TechnologyHarbin Engineering UniversityHarbin 150001China

The task of thiswork is to study the scattering of SHwaves by homogeneous tunnel structures in an unbounded inhomogeneous *** shear modulus is assumed to be a function of coordinates(x,y).Atwo-dimensional scattering model is *** different inhomogeneous parameters,the medium has different properties,expressed as a rigid *** stress concentration phenomenon of the structure is analyzed for material *** on the complex function theory,the expressions of wave field in the tunnel are *** stress concentration phenomenon on the tunnel is discussed with numerical *** distribution of dynamic stress concentration factor on the inner and outer boundaries is analyzed under different influencing ***,it is found that the distribution of dynamic stress concentration factor is significantly affected by the inhomogeneous parameters and reference wave numbers of the medium.

关键词： Inhomogeneous media Shear modulus Complex function theory SH wave Dynamic stress concentration factor(DSCF)

Insights into the regulation mechanism of ring-shaped magnetoelectric energy harvesters via mechanical and magnetic conditions

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Chinese Physics B 2021年第10期30卷 565-576页

作者： yang Shi Ni Li yong yang School of Mechano-Electronic Engineering Xidian UniversityXi’an 710071China Research Center for Applied Mechanics Xidian UniversityXi’an 710071China

This paper presents a theoretical model for predicting and tuning magnetoelectric(ME)effect of ring-shaped composites,in which stress boundary conditions are empoyed and the multi-field coupling property of giant magnetostrictive materials are taken into account.A linear analytical solutions for the closed-and open-circuit ME voltages are derived simultaneously using mechanical differential equations,interface and boundary conditions,and electrical *** nonlinear ME coupling effect,the nonlinear multi-field coupling constitutive equation is reduced to an equivalent form by expanding the strains as a Taylor series in the vicinity of bias magnetic ***,the linear model is generalized to a nonlinear one involving the field-dependent material *** results show that setting a stress-free condition is beneficial for reducing resonance frequency while applying clamped conditions on the inner and outer boundaries may improve the maximum output power *** addition,performing stress conditions on one of the boundaries may enhance ME coupling significantly,without changing the corresponding resonance frequency and optimal *** external stimuli like bias magnetic field and pre-stress are applied to the ring-shaped composites,a novel dual peak phenomenon in the ME voltage curve around resonance frequencies is revealed theoretically,indicating that strong ME coupling may be achieved within a wider bias field ***,the mutual coordination of the bias field and pre-stress may enhance ME coupling as well as tuning the resonance frequency,and thus is pivotal for tunable control of ME energy *** proposed model can be applied to design high-performance energy harvesters by manipulating the mechanical conditions and external stimuli.

关键词： magnetoelectric effect boundary conditions magneto-elastic coupling external stimuli

Theory and application of equivalent transformation relationships between plane wave and spherical wave

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Earthquake Engineering and Engineering Vibration 2017年第4期16卷 773-782页

作者： Wang Yao yang Zailin Zhang Jianwei yang yong College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China

Based on the governing equations and the equivalent models, we propose an equivalent transformation relationships between a plane wave in a one-dimensional medium and a spherical wave in globular geometry with radially inhomogeneous properties. These equivalent relationships can help us to obtain the analytical solutions of the elastodynamic issues in an inhomogeneous medium. The physical essence of the presented equivalent transformations is the equivalent relationships between the geometry and the material properties. It indicates that the spherical wave problem in globular geometry can be transformed into the plane wave problem in the bar with variable property fields, and its inverse transformation is valid as well. Four different examples of wave motion problems in the inhomogeneous media are solved based on the presented equivalent relationships. We obtain two basic analytical solution forms in Examples I and II, investigate the reflection behavior of inhomogeneous half-space in Example III, and exhibit a special inhomogeneity in Example IV, which can keep the traveling spherical wave in constant amplitude. This study implies that our idea makes solving the associated problem easier.

关键词： elastodynamic issue equivalent transformation relationship governing equation inhomogeneous medium

Abelian quotients and orbit sizes of linear groups

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Science China Mathematics 2020年第8期63卷 1523-1534页

作者： Thomas Michael Keller yong yang Department of Mathematics Texas State UniversitySan MarcosTX 78666USA Key Laboratory of Group and Graph Theories and Applications Chongqing University of Arts and SciencesChongqing 402160China

Let G be a finite group,and let V be a completely reducible faithful finite G-module(i.e.,G≤GL(V),where V is a finite vector space which is a direct sum of irreducible G-submodules).It has been known for a long time that if G is abelian,then G has a regular orbit on *** this paper we show that G has an orbit of size at least|G/G′|on *** generalizes earlier work of the authors,where the same bound was proved under the additional hypothesis that G is *** completely reducible modules it also strengthens the 1989 result|G/G′|<|V|by Aschbacher and Guralnick.

关键词： abelian quotients orbits of group actions linear groups