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Wall shear-stress extraction by an optical flow algorithm with a sub-grid formulation

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Acta Mechanica Sinica 2021年第1期37卷 65-79,I0003页

作者： The Hung Tran Lin chen Faculty of Aerospace Engineering Le Quy Don Technical UniversityHanoi10000Vietnam Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100049China

In this study,we developed a novel optical-flow algorithm for determining the wall shear-stress on the surface of objects.The algorithm solves the thin-oil-film equation using a numerical scheme that recovers local features neglected by smoothing filters.A variational formulation with a smoothness constraint was applied to extract the global shear-stress fields.The algorithm was then applied to scalar images generated using direct numerical simulation(DNS)method,which revealed that the errors were smaller than those of conventional methods.The application of the proposed algorithm to recover the wall shear-stress on a low-aspect-ratio wing and on an axisymmetric boattail model taken as examples in this study showed a strong potential for analysing shear-stress fields.Compared to the methods used in previous studies,proposed method reveals more local features of separation line and singular points on object surface.

关键词： Wall shear-stress Optical flow Thin-oil-film equation Sub-grid model

Parameter identification and blanking simulations of DP1000 and Al6082-T6 using Lemaitre damage model

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Advances in Manufacturing 2021年第3期9卷 457-472页

作者： Sheng Cai Lin chen Department of Vehicle Engineering College of EngineeringChina Agricultural UniversityBeijing100083People’s Republic of China CW Bearing GmbH 22113HamburgGermany

This work provides numerical and experimental investigations of blanking process,where the shear-enhanced Lemaitre’s damage model is fully characterized and successfully applied in blanking process to predict the cutting force and cutting edge geometry under different blanking process parameters.Advanced high strength steel DP1000 and an aluminum alloy Al6082-T6 are selected for series of experiments.To obtain the damage parameters in Lemaitre’s damage model the flat rectangular notched specimens tensile test was conducted and the inverse parameter identification procedure was performed.For characterizing the crack closure parameter h in the shear enhanced Lemaitre’s damage model,an in-plane torsion test with novel specimen design was conducted.The finite element model(FEM)of this test was established with the minimum mesh size of 0.01 mm which was consistent with the minimum mesh size in the shear zone of the FEM for blanking process simulation.The longitudinal strain distributions of four kinds of initial notch radius or central-hole specimen were measured and compared with simulation results to validate the FEMs for these four tests.Deformation analysis of blanking of a circular work piece also was performed under three clearances.The effects of blanking conditions on sheared part morphology were detected.Stress triaxiality distribution of the blank sheet was revealed taking advantage of the successfully established FEM.The availability of the testing method and the determination method of the parameters was investigated.

关键词： Blanking Lemaitre damage model Stress triaxiality Finite element model(FEM)

STABILITY OF THE STOCHASTIC θ-METHOD FOR SUPER-linEAR STOCHASTIC DIFFERENTIAL EQUATIONS WITH UNBOUNDED DELAY

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Journal of Computational Mathematics 2019年第5期37卷 704-720页

作者： Lin chen School of Statistics Jiangxi University of Finance and Economics Nanchang 330013China Research Center of Applied Statistics Jiangxi University of Finance and Economics Nanchang 330013China

This paper deals with numerical stability properties of super-linear stochastic differential equations with unbounded delay. Sufficient conditions for mean square and almost sure decay stability of the above system and its stochastic θ-method approximation are investigated in this paper. The author establishes numerical stability under a monotone-type condition in unbounded delay setting. An example is presented to illustrate the result.

关键词： Unbounded delay Monotone condition Polynomial condition Stochastic θ- method Decay stability.

Experimental and numerical investigations of the mechanical behavior of half sandwich laminate in the context of blanking

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Advances in Manufacturing 2020年第2期8卷 177-188页

作者： Sheng Cai Lin chen Department of V ehicle Engineering College of EngineeringChina Agricultural UniversityBeijing 100083People's Republic of China CW Bearing GmbH Hamburg 22113Germany

In this study,the complex mechanical behavior of an aluminum/low-density polyethylene(LDPE)half sandwich structure was investigated during the blanking process.Mechanical tests were conducted for the polymer and metal layer and the delamination behavior of the adhesive between the two layers.A new testing device was designed for detecting the delamination under tensile mode.Corresponding finite element models were established for the mechanical tests of the metal layer and the delamination of both layers for inverse parameter identifcation.Material parameters for Lemaitre-type damage,Drucker-Prager,and cohesive zone modeIs were identified for the metal,polymer,and adhesive,respectively.A finiteelement(FE)model was established for the blanking process of the sandwich structures.The experimental forcedisplacement curves,obtained in the blanking process of the half sandwich sheet,were compared with the predicted results of the FE model.The results showed that the predicted force-displacement curves and the experimental results were in good agreement.Additionally,the correlation between cutting clearance and changes in the forcedisplacement curves was obtained.Three feature values quantitatively described the imperfection of the experimental cutting edge.The effect of punch clearance on these values was studied numerically and experimentally.The results indicated that a smaller clearance generated a better cutting-edge quality.The stress state of the half sandwich structure during blanking was analyzed using the established FE model.

关键词： Sandwich plates Blanking Continuum damage mechanics(CDM) Drucker-Prager model Cohesive zone model

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首届全国教材建设奖先进个人陈琳教授访谈

外语教育研究前沿 2022年第2期5卷 29-33,91页

作者：张黎新陈琳外语教学与研究出版社北京外国语大学

陈琳教授编写了多部外语教育经典教材,获评首届全国教材建设奖“全国教材建设先进个人”。在对陈教授的采访中,他就“全国教材建设奖项对教材建设与研究的推动作用、近年来我国外语教育改革取得的重要成果、优秀教材的评判标准、《普通... 详细信息

陈琳教授编写了多部外语教育经典教材,获评首届全国教材建设奖“全国教材建设先进个人”。在对陈教授的采访中,他就“全国教材建设奖项对教材建设与研究的推动作用、近年来我国外语教育改革取得的重要成果、优秀教材的评判标准、《普通高中英语课程标准(2017年版)》提出核心素养的意义、由他主编的获奖教材《英语》(新标准)融入他多年来积累的外语教学经验和理念、21世纪以来外语教学理论及实践的发展变化以及他对今后外语教学实践的建议”等方面作了详细的介绍。

关键词：全国教材建设奖教材建设优秀教材外语教学理论与实践

Study on Acoustic Performance for Diatom Frustule with Nanoporous Structure

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Journal of Bionic Engineering 2023年第4期20卷 1656-1669页

作者： Fanming Meng Yong Zheng Hongxia Wang Lin chen College of Mechanical Engineering Hubei University of Automotive TechnologyShiyan442002China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

The acoustic performance for the nanoporous frustule of the diatom is studied based on the computational fluid dynamics theory and acoustic theory involved.Representative Coscinodiscus sp.frustule is observed through the scanning electron microscope and modeled by the commercial software Solidworks.Further,the acoustic performance for the Coscinodiscus sp.frustule is studied at the varied depth,diameter or interval of the pore,as well as the film thickness of the fluid surrounding the Coscinodiscus sp.frustule.The numerical results show that,when the upper and lower pore diameters are separately 200 and 300 nm,the upper and lower pore depths are separately 200 and 250 nm,and both the pore interval and fluid film thickness are 500 nm,the elaborate nanoporous structure of Coscinodiscus sp.frustule can lower its acoustic power level by 17.49%,compared with that without porous structure.Meanwhile,the double-layer pore of Coscinodiscus sp.frustule can decrease its acoustic power level by 12.69%,compared with its single-layer pore structures.

关键词： Acoustic performance Nanoporous structure Diatom Computational fluid dynamics

Mie scatterers bring a resonator to an exceptional point

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Light(Science & Applications) 2023年第9期12卷 1715-1716页

作者： Kai Hong Lin chen Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan430074China

Exceptional points have given rise to many intriguing optical phenomena that are of fundamental importance for a variety of breakthrough technologies.The pre-defined Mie scatterers can bring a resonator to an exceptio... 详细信息

关键词： resonator scattering. exceptional

Thermal and Mechanical Properties Optimization of ABO4 Type EuNbO4 By the B-Site Substitution of Ta

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Engineering 2020年第2期6卷 178-185页

作者： Lin chen Jing Feng Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093China

Ferroelastic ABO4 type RETaO4 and RENbO4 ceramics(where RE stands for rare earth)are being investigated as promising thermal barrier coatings(TBCs),and the mechanical properties of RETaO4 have been found to be better than those of RENbO4.In this work,B-site substitution of tantalum(Ta)is used to optimize the thermal and mechanical properties of EuNbO4 fabricated through a solid-state reaction(SSR).The crystal structure is clarified by means of X-ray diffraction(XRD)and Raman spectroscopy;and the surface microstructure is surveyed via scanning electronic microscope(SEM).The Young’s modulus and the thermal expansion coefficient(TEC)of EuNbO4 are effectively increased;with respective maximum values of 169 GPa and 11.2×10^-6 K^-1(at 1200℃).The thermal conductivity is reduced to 1.52 W·K^-1·m^-1(at 700℃),and the thermal radiation resistance is improved.The relationship between the phonon thermal diffusivity and temperature was established in order to determine the intrinsic phonon thermal conductivity by eliminating the thermal radiation effects.The results indicate that the thermal and mechanical properties of EuNbO4 can be effectually optimized via the B-site substitution of Ta,and that this proposed material can be applied as a high-temperature structural ceramic in future.

关键词： Thermal barrier coatings Rare earth niobates Substitution Thermal conductivity Thermal expansion coefficients Young’s modulus

Methionine oxidation and reduction of the ethylene signaling component MaEIL9 are involved in banana fruit ripening

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Journal of Integrative Plant Biology 2023年第1期65卷 150-166页

作者： Lisha Zhu Lin chen Chaojie Wu Wei Shan Danling Cai Zengxiang lin Wei Wei Jianye chen Wangjin Lu Jianfei Kuang State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables/Engineering Research Center of Southern Horticultural Products Preservation Ministry of EducationCollege of Horticulture South China Agricultural UniversityGuangzhou 510642 China Key Laboratory of Biology and Genetic Improvement of Horticultural Crops(South China) Ministry of Agriculture and Rural AffairsCollege of Horticulture South China Agricultural UniversityGuangzhou 510642 China

The ethylene insensitive 3/ethylene insensitive3-like(EIN3/EIL)plays an indispensable role in fruit ripening.However,the regulatory mechanism that links post-translational modification of EIN3/EIL to fruit ripening is largely unknown.Here,we studied the expression of 13 MaE IL genes during banana fruit ripening,among which MaE IL9 displayed higher enhancement particularly in the ripening stage.Consistent with its transcript pattern,abundance of MaE IL9 protein gradually increased during the ripening process,with maximal enhancement in the ripening.DNA affinity purification(DAP)-seq analysis revealed that MaE IL9 directly targets a subset of genes related to fruit ripening,such as the starch hydrolytic genes MaA MY3D and MaB AM1.Stably overexpressing MaE IL9 in tomato fruit hastened fruit ripening,whereas transiently silencing this gene in banana fruit retarded the ripening process,supporting a positive role of MaEIL9 in fruit ripening.Moreover,oxidation of methionines(Met-129,Met-130,and Met-282)in MaEIL9 resulted in the loss of its DNA-binding capacity and transcriptional activation activity.Importantly,we identified MaEIL9 as a potential substrate protein of methionine sulfoxide reductase A MaMsrA4,and oxidation of Met-129,Met-130,and Met-282in MaEIL9 could be restored by MaMsrA4.Collectively,our findings reveal a novel regulatory network controlling banana fruit ripening,which involves MaMsrA4-mediated redox regulation of the ethylene signaling component MaEIL9.

关键词： banana EIN3/EIL redox regulation ROS starch degradation