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AN UNSPLIT LAGRANGIAN ADVECTION SCHEME FOR VOLUME OF FLUID METHOD

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Journal of Hydrodynamics 2010年第1期22卷 73-80页

作者： YANG Wei LIU Shu-hong wu yu-lin Laboratory of Hydraulic Science and Engineering Tsinghua University Beijing 100084 China

An Unsplit Lagrangian Advection （ULA） scheme for Volume Of Fluid （VOF） method is presented in this article. The ULA scheme is developed based on an algorithm of Piecewise linear Interface Construction （PLIC）. The volume fluxes between cells are calculated through solving the new equation of the linear interfaces in cells in the ULA scheme. The fluxes flowing out from one cell is the inflow fluxes for another cell. In this way the whole fluid volume is conserved strictly without using any redistribution algorithms. The ULA scheme is based on two-dimensional structured rectangular mesh and may be extended to three-dimensional structured mesh with more geometrical efforts. The results from three widely-used benchmark tests show that the ULA scheme can achieve the accuracy higher than Split Lagaragian Advection （SLA） scheme and the Flux-Corrected Transport （FCT） algorithm.

关键词： advection schemes free surfaces fluid interfaces Volume Of Fluid (VOF) method

Genotoxicity evaluation and a primary risk assessment of organic pollutants in the drinking water sources of Nanjing, China

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Journal of Environmental Sciences 2006年第5期18卷 983-988页

作者： LI Yi-qiang wu yu-lin CHEN yuan-gao KONG Zhi-ming The State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Nanjing University Nanjing 210093 China National Accredited Laboratory Environmental Monitoring Center of Jiangsu Province Nanjing 210036 China

An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.

关键词： genotoxicity comet assay risk assessment organic pollutants drinking water sources Nanjing City

Device design principles and bioelectronic applications for flexible organic electrochemical transistors

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International Journal of Extreme Manufacturing 2024年第1期6卷 126-153页

作者： lin Gao Mengge wu Xinge yu Junsheng yu State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China(UESTC)Chengdu 610054People’s Republic of China Department of Biomedical Engineering City University of Hong KongHong Kong Special Administrative Region of ChinaPeople’s Republic of China

Organic electrochemical transistors(OECTs) exhibit significant potential for applications in healthcare and human-machine interfaces, due to their tunable synthesis, facile deposition, and excellent biocompatibility. Expanding OECTs to the fexible devices will significantly facilitate stable contact with the skin and enable more possible bioelectronic applications. In this work,we summarize the device physics of fexible OECTs, aiming to offer a foundational understanding and guidelines for material selection and device architecture. Particular attention is paid to the advanced manufacturing approaches, including photolithography and printing techniques, which establish a robust foundation for the commercialization and large-scale fabrication. And abundantly demonstrated examples ranging from biosensors, artificial synapses/neurons, to bioinspired nervous systems are summarized to highlight the considerable prospects of smart healthcare. In the end, the challenges and opportunities are proposed for fexible OECTs. The purpose of this review is not only to elaborate on the basic design principles of fexible OECTs, but also to act as a roadmap for further exploration of wearable OECTs in advanced bio-applications.

关键词： flexible organic electrochemical transistors wearable bioelectronics manufacturing approaches device physics neuromorphic applications

Unsteady Cavitating Flow around a Hydrofoil Simulated Using the Partially-Averaged Navier-Stokes Model

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Chinese Physics Letters 2012年第7期29卷 198-202页

作者： JI Bin LUO Xian-wu wu yu-lin XU Hong-yuan State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084

Numerical simulations of unsteady cavitating flow around a NACA66-mod hydrofoil were performed using the partially-averaged Navier-Stokes method with different values of the resolution control parameters (f k =1.0-0.2,fε =1).With decreasing fk,the predicted cavitating flow becomes unsteady as the time-averaged turbulent viscosity at the rear part of the attached cavity is gradually *** fk =0.9 and 0.8,the cavity becomes unstable and its length dramatically expands and shrinks,but the calculation fails to predict the vapor cloud shedding behavior observed *** smaller fk less than 0.7,the cloud shedding behavior is simulated numerically and the predicted cavity shedding frequency *** fk =0.2,the whole cavitating flow evolution can be reasonably reproduced including the cavity growth/destabilization observed *** reentrant flow along the suction surface of the hydrofoil is the main trigger to cause the vapor cloud *** wall pressure along the hydrofoil surface oscillates greatly due to the dynamic cavity *** the simulations and experiments,it is confirmed that for the PANS method,resolution control parameters of fk =0.2and fε =1 are recommended for numerical simulations of unsteady cavitating ***,the present study shows that the PANS method is an effective approach for predicting unsteady cavitating flow over hydrofoils.

关键词： unsteady Navier averaged

PERIODIC BOUNDARY CONDITION IN SIMULATION OF TURBULENT FLOW

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Journal of Hydrodynamics 2002年第3期14卷 111-116页

作者： Zhou, Xiao-Quan Cao, Shu-You Qu, Lun-Fu wu, yu-lin Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China Dept. of Thermal Eng. Tsinghua Univ. Beijing 100084 China

The simulations of the three-dimensional turbulent flows through hydraulic turbine components[1] were conducted based on the standard k-Ε turbulent model with body-fitted coordinates and staggering grid system. The SIMPLEC algorithm was adopted in the numerical procedure. A new method to treat the periodic boundary condition was used. The calculated results of the new method were compared with those of traditional ones. These results indicate that the new method can give much better results, and can be used in simulating flow through rotational impellers. The presented method can be combined with alternative turbulent model or employed in large eddy simulation.

关键词： Computer simulation Hydraulic turbines Impellers Three dimensional Time varying systems

MOF-derived Hierarchical Hollow NiRu-C Nanohybrid for Efficient Hydrogen Evolution Reaction

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Chinese Journal of Structural Chemistry 2021年第10期40卷 1346-1356页

作者： wu yu-lin XIE Ning LI Xiao-Fang FU Zhao-Ming wu Xin-Tao ZHU Qi-Long College of Chemistiy Fuzhou UniversityFuzhou 350108China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information oj China Fuzhou 350108China University of Chinese Academy of Sciences Beijing 100049China Physics and Electronic Information College Yunnan Normal UniversityKunming 650500China

Designing efficient electrocatalysts for efficient hydrogen evolution is extremely desired but challenging. Herein, we report a facile MOF-assisted strategy to synthesize the hierarchical hollow spherical NiRu-C nanohybrid with closely packed rod-like bulges on the surface. Benefited from the more exposed active sites of NiRu-C nanohybrid and the efficient electron/mass transport in its unique hierarchical hollow spherical nanostructure, the optimized nanohybrid showed excellent performance for alkaline hydrogen evolution with ultralow overpotentials, which are much superior to those of Pt/C and the overwhelming majority of reported electrocatalysts. The interpretation of the reaction mechanism was further discussed with DFT calculations. Our research may provide a guidance for the development of advanced electrocatalysts with controlled morphology and excellent performance for future energy applications.

关键词： hydrogen evolution reaction NiRu hollow spherical nanostructure electrocatalysis

Continuous Cooling Transformation Behavior and Kinetic Models of Transformations for an Ultra-Low Carbon Bainitic Steel

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Journal of Iron and Steel Research International 2012年第12期19卷 73-78页

作者： ZHANG Zhi-min CAI Qing-wu yu Wei LIXiao-lin WANG Li-dong Metallurgical Engineering Research Institute University of Science and Technology Beijing Beijing 100083 China

The aim was to investigate transformation behavior and transformation kinetics of an ultra-low carbon bai- nitic steel during continuous cooling. Continuous cooling transformation （CCT） curves of tested steel were measured by thermal dilatometer and metallographic structures at room temperature were observed by optical microscope. Then transformation kinetic equation of austenite to ferrite as well as austenite to bainite was established by analyzing the relationship of lnln]-l/（1--f）] and lnt in the kinetic equation on the basis of processed experimental data. Finally, the measured and calculated kinetic behaviors of the steel during continuous cooling were compared and growth pat- terns of transformed ferrite and bainite were analyzed. Results showed that calculated result was in reasonable agree- ment with the experimental data. It could be concluded that the growth modes of transformed ferrite and bainite were mainly one dimension as the Avrami exponents were between 1 and 2.

关键词： ultra low carbon bainitic steel continuous cooling transformation kinetics Avrami equation

LES NUMERICAL SIMULATION OF CAVITATION BUBBLE SHEDDING ON ALE 25 AND ALE 15 HYDROFOILS

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Journal of Hydrodynamics 2009年第6期21卷 807-813页

作者： LIU De-min LIU Shu-hong wu yu-lin XU Hong-yuan State Key Laboratory of Hydro Science and Hydraulic Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

A cavitation calculation scheme is developed and applied to ALE 15 and ALE 25 hydrofoils, based on the Bubble Two-phase Flow （BTF） cavity model with a Large Eddy Simulation （LES） methodology. The Navier-Stokes equations including cavitation bubble clusters are solved through the finite-volume approach with a time-marching scheme. Simulations are carried out in a 3-D field with a hydrofoil ALE 15 or ALE 25 at an angle of attack of 8^0 and cavitation number σ = 2.3 with α 2× 10^6, meshing system. With the time-marching, the cavitation bubble gradually grows to a steady lump shape and then produces an irregular small bubble behind the main cavitation bubble, finally shedding from the leading edge of the cloud cavitation structure. The calculated results including velocity field and pressure field are consistent with experiment data at the same Reynolds number and cavitation number. The vortex and reverse flow are observed on the hydrofoil surface.

关键词： cavitation ALE hydrofoil Large Eddy Simulation (LES)

Microstructure recognition of steels by machine learning based on visual attention mechanism

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Journal of Iron and Steel Research International 2024年第4期31卷 909-923页

作者： Xing-yu Chen lin Cheng Cheng-yang Hu yu-peng Zhang Kai-ming wu The State Key Laboratory of Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science on Metallurgical ProcessingInternational Research Institute for Steel TechnologyCollaborative Center on Advanced SteelsWuhan University of Science and TechnologyWuhan 430081HubeiChina Metals Valley and Band(Foshan)Metallic Composite Materials Co. Ltd.Foshan 528000GuangdongChina

U-Net has achieved good performance with the small-scale datasets through skip connections to merge the features of the low-level layers and high-level layers and has been widely utilized in biomedical image segmentation as well as recent microstructure image segregation of the *** representative visual attention mechanism modules,named as squeeze-and-excitation networks,convolutional block attention module,and extended calibration algorithm,were intro-duced into the traditional U-Net architecture to further improve the prediction *** is found that compared with the original U-Net architecture,the evaluation index of the improved U-Net architecture has been significantly improved for the microstructure segmentation of the steels with the ferrite/martensite composite microstructure and pearlite/ferrite composite microstructure and the complex martensite/austenite island/bainite microstructure,which demonstrates the advantages of the utilization of the visual attention mechanism in the microstructure *** reasons for the accuracy improvement were discussed based on the feature maps analysis.

关键词： Microstructure recognition-Steel Machine learning Visual attention mechanism Visualization