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PARTIALLY AVERAGED NAVIER-STOKES METHOD FOR TIME-DEPENDENT TURBULENT CAVITATING FLOWS

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Journal of Hydrodynamics 2011年第1期23卷 26-33页

作者： HUANG biao WANG Guo-yu School of Vehicle and Transportation Engineering Beijing Institute of Technology Beijing 100081 China

Cavitation typically occurs when the fluid pressure is lower than the vapor pressure in a local thermodynamic state,and the flow is frequently unsteady and *** Reynolds-Averaged Navier-Stokes（RANS）approach has been popular for turbulent flow *** most widely used ones,such as the standard k-εmodel,have well-recognized deficiencies when treating time dependent flow *** identify ways to improve the predictive capability of the current RANS-based engineering turbulence closures,conditional averaging is adopted for the Navier-Stokes equation,and one more parameter,based on the filter size,is introduced into the k-ε*** the Partially Averaged Navier-Stokes（PANS）model,the filter width is mainly controlled by the ratio of unresolved-to-total kinetic *** model is assessed in unsteady cavitating flows over a Clark-Y *** the experimental validations regarding the forces,frequencies,cavity visualizations and velocity distributions,the PANS model is shown to improve the predictive capability considerably,in comparison to the standard k-ε model,and also,it is observed the value of1f in the PANS model has substantial influence on the predicting *** the filter width1f is decreased,the PANS model can effectively reduce the eddy viscosity near the closure region which can significantly influence the capture of the detach cavity,and this model can reproduce the time-averaged velocity quantitatively around the hydrofoil.

关键词： cavitating flow PANS model filter width unresolved-to-total kinetic energy

A structural health assessment method for shield tunnels based on torsional wave speed

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Science China(Technological Sciences) 2014年第6期57卷 1109-1120页

作者： ZHOU biao XIE XiongYao LI YongSheng Key Laboratory of Geotechnical & Underground Engineering Ministry of EducationTongji University Department of Geotechnical Engineering Tongji University

Following recent rapid developments in tunnel engineering in China,the heavy structural maintenance work of the future is likely to pose a great *** developed vibration-based health assessment and monitoring methods offer good prospects for large-scale structural monitoring,hidden surface detection and disease ***,because the dynamic properties of tunnels are sensitive to the coupling and damping effects of the surrounding soil,there is little relevant research on tunnel *** the PiP(pipe in pipe)model,the intrinsic tunnel modes and their response characteristics are investigated in this paper,and the degree to which the identification of these characteristics is influenced by mode superposition and the soil coupling effect are also *** response features of these flexible wave modes are found to be barely recognizable in a tunnel-soil coupled system,while the phase velocity of the torsional wave can be determined by combining phase spectrum analysis and the HHT(Hilbert-Huang transformation)method.A new structural health assessment method based on the torsional wave speed is therefore *** this method,the torsional wave speed is used to determine the tunnel structure’s global stiffness based on a newly developed dispersion *** calculated stiffness is then used to evaluate the tunnel’s structural service status.A field test was also carried out at a newly built tunnel to validate the proposed method;the tunnel structure’s Young’s modulus was obtained and was very close to the designed *** indicates that this method is an effective way to assess tunnel service conditions,and also provides a theoretical basis for future applications to health assessment of shield tunnels.

关键词： shield tunnel condition assessment torsional wave mode phase velocity

Geochemistry, Monazite U–Pb Dating, and Li–Nd Isotopes of the Madi Rare Metal Granite in the Northeastern Part of the North China Craton

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Acta Geologica Sinica(English Edition) 2019年第4期93卷 901-911页

作者： HOU Jianglong JIANG biao DAI Hongzhang MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

The Madi rare metal granite is a complex massif,which contains a variety of rare metals,such as Nb,Ta,Li,and *** this paper,the geochemical characteristics of the granite were obtained by multi-collector inductively coupled mass spectrometry(MC-ICP-MS).The precise crystalline age of the granite was obtained from monazite U-Pb dating,and the source of the granite was determined using Li-Nd *** Madi rare metal granite is a high-K(calc-alkaline),peraluminous,S-type *** U-Pb monazite age indicates that the crystalline age of the granite is 175.6 Ma,which is Early *** granite is characterized by a relatively wide range ofδ7 Li values(+2.99‰to+5.83‰)and high lithium concentrations(181 ppm to 1022 ppm).The lithium isotopic composition of the granite does not significantly correlate with the degree of magmatic *** insignificant amount of lithium isotope fractionation occurred during the granitic *** lithium isotopic composition of the granite significantly differs from that of the wall rock,but it is very similar to that of a primitive mantle peridotite xenolith(meanδ7 Li value+3.5‰).The plot of Li concentration versusδ7 Li indicates that the Li isotopic composition of the granite is similar to that of island arc *** on the above-described evidence,the granite was mainly derived from the crust,but it was contaminated by a deep granitic magma.

关键词： geochemistry U-Pb monazite age Li-Nd isotopes crystallization age magmatic source Madi rare metal granite

Numerical simulation of unsteady cavitating flows around a transient pitching hydrofoil

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Science China(Technological Sciences) 2014年第1期57卷 101-116页

作者： HUANG biao WU Qin WANG GuoYu School of Mechanical and Vehicular Engineering Beijing Institute of Technology

The objective of this paper is to improve the understanding of the influence of multiphase flow on the turbulent closure model, the interplay between vorticity fields and cavity dynamics around a pitching hydrofoil. The effects of pitching rate on the sub- cavitating and cavitating response of the pitching hydrofoil are also investigated. In particular, we focus on the interactions between cavity inception, growth, and shedding and the vortex flow structures, and their impacts on the hydrofoil performance. The calculations are 2-D and performed by solving the incompressible, multiphase Unsteady Reynolds Averaged Navier Stokes （URANS） equations via the commercial CFD code CFX. The k-co SST （Shear Stress Transport） turbulence model is used along with the transport equation-based cavitation models. The density correction function is considered to reduce the eddy viscosity according to the computed local fluid mixture density. The calculation results are validated with experiments conducted by Ducoin et al. （see Computational and experimental investigation of flow over a transient pitching hydrofoil, Eur J Mech/B Fluids, 2009, 28：728-743 and An experimental analysis of fluid structure interaction of a flexible hydrofoil in vari- ous flow regimes including cavitating flow, Eur J Mech B/fluids, 2012, 36： 63-74）. Results are shown for a NACA66 hydro- foil subject to slow （quasi static, t2=6~/s, ＆＊ =0.18） and fast （dynamic, ＆=63~/s, dr＂ =1.89） pitching motions from a =0~ to a =15~. Both subcavitaing （or =8.0） and cavitating （cr=3.0） flows are considered. For subcavitating flow （or=8.0）, low frequency fluctuations have been observed when the leading edge vortex shedding occurs during stall, and delay of stall is ob- served with increasing pitching velocity. For cavitating flow （tr=3.0）, small leading edge cavities are observed with the slow pitching case, which significantly modified the vortex dynamics at high angles of attack, leading to high frequency fluctuations of the

关键词： unsteady cavitating flow pitching hydrofoil turbulence model

Multisoliton solutions with even numbers and its generated solutions for nonlocal Fokas–Lenells equation

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Communications in Theoretical Physics 2020年第12期72卷 94-98页

作者： Rong Fan Zhao Zhang biao Li School of Mathematics and Statistics Ningbo UniversityNingbo 315211China

In this letter,we investigate multisoliton solutions with even numbers and its generated solutions for nonlocal Fokas–Lenells equation over a nonzero ***,we obtain 2 n-soliton solutions with a nonzero background via n-fold Darboux transformation,and find that these soliton solutions will appear in ***,2 n-soliton solutions consist of n‘bright’solitons and n‘dark’*** phenomenon implies a new form of integrability:even *** interactions between solitons with even numbers and breathers are studied in *** our best knowledge,a novel nonlinear superposition between a kink and 2 n-soliton is also generated for the first ***,interactions between some different smooth positons with a nonzero background are derived.

关键词： 2n-soliton positon solutions hybrid solutions

Effects of pore structure and distribution on strength of porous Cu-Sn-Ti alumina composites

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Chinese Journal of Aeronautics 2017年第6期30卷 2004-2023页

作者： biao ZHAO Tianyu YU Wenfeng DING Xianying LI College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Department of Aerospace Engineering Iowa State University

Porous Cu-Sn-Ti alumina composites were fabricated by sintering Cu-Sn-Ti alloy powders, graphite particles, and alumina hollow particles agent. The effects of the pore structure and distribution on the composites strength were evaluated. Different pore distributions were modeled by using finite element analysis to investigate the tensile strength of the composites. Furthermore, a fractal analysis-based box-covering algorithm was used on the Cu-Sn-Ti alumina composites topology graphs to better investigate the pore structure and distribution. Results obtained show that different sizes and concentrations of alumina hollow particles could result in different porosities from20% to 50%. A larger pore size and a higher pore concentration reduce the strength, but provide more space for chip formation as a bonding material of a grinding wheel. The body-centered pore structure of the composites shows the highest stress under a tension load. The original composites topology graphs have been transformed to ordered distributed pore graphs based on the total pore area conservation. The information dimension magnitude difference between the original topology graphs and the ordered distributed circulars graphs is found to be linear with the Cu-Sn-Ti alumina composites strength. A larger difference renders a lower flexural strength, which indicates that uniform ordered distributed pores could benefit the composites strength.

关键词： Finite element analysis(FEA) Metal-matrix composites(MMCs) Microstructurat analysis Pore structure Strength

Exact Analytical Solutions in Bose-Einstein Condensates with Time-Dependent Atomic Scattering Length

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Communications in Theoretical Physics 2007年第1期47卷 143-148页

作者： CHEN Yong LI biao ZHENG Yu Nonlinear Science Center and Department of Mathematics Ningbo University Ningbo 315211 China Department of Mathematics East China Normal University Shanghai 200062 China MM Key Lab the Chinese Academy of Sciences Beijing 100080 China

In the paper, the generalized Riccati equation rational expansion method is presented. Making use of the method and symbolic computation, we present three families of exact analytical solutions of Bose-Einstein condensates with the time-dependent interatomic interaction in an expulsive parabolic potential. Then the dynamics of two anlytical solutions are demonstrated by computer simulations under some selectable parameters including the Feshbach-managed nonlinear coefficient and the hyperbolic secant function coefficient.

关键词： NLS equation soliton symbolic computation

Long Non-coding RNAs and Their Roles in Non-small-cell Lung Cancer

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Genomics, Proteomics & Bioinformatics 2016年第5期14卷 280-288页

作者： Ming-Ming Wei Guang-biao Zhou State Key Laboratory of Membrane Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

As a leading cause of cancer deaths worldwide, lung cancer is a collection of diseases with diverse etiologies which can be broadly classified into small-cell lung cancer （SCLC） and non-small-cell lung cancer （NSCLC）. Lung cancer is characterized by genomic and epigenomic alterations; however, mechanisms underlying lung tumorigenesis remain to be elucidated. Long noncoding RNAs （lncRNAs） are a group of non-coding RNAs that consist of ≥ 200 nucleotides but possess low or no protein-coding potential. Accumulating evidence indicates that abnormal expression of lncRNAs is associated with tumorigenesis of various cancers, including lung cancer, through multiple biological mechanisms involving epigenetic, transcriptional, and post-transcriptional alterations. In this review, we highlight the expression and roles of lncRNAs in NSCLC and discuss their potential clinical applications as diagnostic or prognostic biomarkers, as well as therapeutic targets.

关键词： Long non-coding RNA Non-small-cell lung cancer Expression spectrum Biomarker Therapeutic resistance

Performing Laboratory Network Surveillance to Monitor the Emergence and Spread of Infectious Diseases

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China CDC weekly 2022年第12期4卷 233-234页

作者： biao Kan National Institute for Communicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina State Key Laboratory of Infectious Disease Prevention and Control BeijingChina

Laboratory systems are one of the pillars in the infrastructure for infectious disease control and prevention——surveillance,early warning,and emergency response capacities are a priority to public *** based monitoring provides essential support for infection diagnosis,pathogen identification,spread tracking,and outbreak warning,especially for emerging infections caused by newly recognized pathogens and clusters of unknown diseases.

关键词： Laboratory prevention diagnosis