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Active control of flow past an elliptic cylinder using an artificial neural network trained by deep reinforcement learning

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Applied Mathematics and Mechanics(English Edition) 2022年第12期43卷 1921-1934页

作者： Bofu WANG Qiang WANG Quan ZHOU yulu liu Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Shanghai Frontiers Science Base for Mechanoinfomatic Shanghai UniversityShanghai 200072China School of Science Shanghai Institute of TechnologyShanghai 201418China

The active control of flow past an elliptical cylinder using the deep reinforcement learning(DRL)method is *** axis ratio of the elliptical cylinderΓvaries from 1.2 to 2.0,and four angles of attackα=0°,15°,30°,and 45°are taken into consideration for a fixed Reynolds number Re=*** mass flow rates of two synthetic jets imposed on different positions of the cylinderθ1andθ2are trained to control the *** optimal jet placement that achieves the highest drag reduction is determined for each *** a low axis ratio ellipse,i.e.,Γ=1.2,the controlled results atα=0°are similar to those for a circular cylinder with control jets applied atθ1=90°andθ2=270°.It is found that either applying the jets asymmetrically or increasing the angle of attack can achieve a higher drag reduction rate,which,however,is accompanied by increased *** control jets elongate the vortex shedding,and reduce the pressure ***,the flow topology is modified at a high angle of *** an ellipse with a relatively higher axis ratio,i.e.,Γ1.6,the drag reduction is achieved for all the angles of attack *** larger the angle of attack is,the higher the drag reduction ratio *** increased fluctuation in the drag coefficient under control is encountered,regardless of the position of the control *** control jets modify the flow topology by inducing an external vortex near the wall,causing the drag *** results suggest that the DRL can learn an active control strategy for the present configuration.

关键词： drag reduction deep reinforcement learning(DRL) elliptical cylinder active control

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Scale properties of turbulent transport and coherent structure in stably stratified flows

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Applied Mathematics and Mechanics(English Edition) 2016年第4期37卷 443-458页

作者： Long ZHU Xiang QIU Jianping LUO yulu liu School of Mechanical Engineering Shanghai Institute of Technology School of Science Shanghai Institute of Technology Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

The empirical mode decomposition （EMD） is used to study the scale properties of turbulent transport and coherent structures based on velocity and temperature time series in stably stratified turbulence. The analysis is focused on the scale properties of intermittency and coherent structures in different modes and the contributions of energy-contained coherent structures to turbulent scalar counter-gradient transport （CGT）. It is inferred that the velocity intermittency is scattered to more modes with the development of the stratified flow, and the intermittency is enhanced by the vertical stratification, especially in small scales. The anisotropy of the field is presented due to different time scales of coherent structures of streamwise and vertical velocities. There is global counter-gradient heat transport close to the turbulence-generated grid, and there is local counter-gradient heat transport at certain modes in different positions. Coherent structures play a principal role in the turbulent vertical transport of temperature.

关键词： stratified turbulence coherent structure counter-gradient transport (CGT),empirical mode decomposition (EMD)

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Asymptotic solutions of the flow of a Johnson-Segalman fluid through a slowly varying pipe using double perturbation strategy

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Applied Mathematics and Mechanics(English Edition) 2018年第2期39卷 169-180页

作者： Xinyin ZOU Xiang QIU Jianping LUO Jiahua LI P.N.KALONI yulu liu School of Mechanical Engineering Shanghai Institute of Technology School of Science Shanghai Institute of Technology College of Urban Construction and Safety Engineering Shanghai Institute of Technology Department of Mathematics and Statistics University of Windsor Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

A double perturbation strategy is presented to solve the asymptotic solutions of a Johnson-Segalman （J-S） fluid through a slowly varying pipe. First, a small parameter of the slowly varying angle is taken as the small perturbation parameter, and then the second-order asymptotic solution of the flow of a Newtonian fluid through a slowly varying pipe is obtained in the first perturbation strategy. Second, the viscoelastic parameter is selected as the small perturbation parameter in the second perturbation strategy to solve the asymptotic solution of the flow of a J-S fluid through a slowly varying pipe. Finally, the parameter effects, including the axial distance, the slowly varying angle, and the Reynolds number, on the velocity distributions are analyzed. The results show that the increases in both the axial distance and the slowly varying angle make the axial velocity slow down. However, the radial velocity increases with the slowly varying angle, and decreases with the axial distance. There are two special positions in the distribution curves of the axial velocity and the radial velocity with different Reynolds numbers, and there are different trends on both sides of the special positions. The double perturbation strategy is applicable to such problems with the flow of a non-Newtonian fluid through a slowly varying pipe.

关键词： Johnson-Segalman (J-S) fluid slowly varying pipe double perturbationstrategy velocity distribution

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Lagrangian coherent structures and their heat-transport mechanism in the turbulent Rayleigh-Bénard convection

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Science China(Technological Sciences) 2022年第4期65卷 966-976页

作者： CHENG Hang SHEN Jie ZHANG YiZhao ZHOU Quan CHONG Kai Leong liu yulu LU ZhiMing Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering and School of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China The School of Sciences Shanghai Institute of TechnologyShanghai 200072China

In this paper,we investigate the Lagrangian coherent structures(LCSs)and their heat-transport mechanism in turbulent Rayleigh-Bénard(RB)*** numerical simulations(DNS)are performed in a closed square cell with Rayleigh numbers(Ra)ranging from 10^(6) to 10^(9) and Prandtl(Pr)number fixed at Pr=***,our results show the power-law relationship between Nusselt number(Nu)and Ra,Nu=0.99Ra^(0.30±0.02),confirming the results from previous *** gain insights into the material transport,LCSs are extracted using the finite-time Lyapunov exponent(FTLE)***,lobe structures are widely present,and we elucidate their role in transporting heat from the corner rolls to large-scale ***,the relationships between LCSs and thermal plumes are examined,and we identify two behaviors of thermal plumes:first,most plumes transport along the LCSs;second,few plumes are exposed to the bulk and subsequently mix with the turbulent ***,we quantify the heat flux along the LCSs,which contributes to about 85%of the total flux regardless of *** suggests that LCSs play a significant role in heat ***,the viscous(thermal)dissipation rate along the LCSs is quantified,which is larger than 80%(60%)of the total value,suggesting that LCSs are responsible for the large viscous and thermal dissipations.

关键词： Rayleigh-Bénard convection finite-time Lyapunov exponent Lagrangian coherent structures

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Efficient reduction of hexavalent chromium with microscale Fe/Cu bimetals:Efficiency and the role of Cu

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Chinese Chemical Letters 2023年第6期34卷 225-229页

作者： Yue Yuan Zhikui Zhou Xinyi Zhang Xin Li yulu liu Shengtao Yang Bo Lai Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission School of Chemistry and EnvironmentSouthwest Minzu UniversityChengdu 610041China Key Laboratory of General Chemistry of the National Ethnic Affairs Commission School of Chemistry and EnvironmentSouthwest Minzu UniversityChengdu 610041China College of Resource and Environment Chengdu University of Information TechnologyChengdu 610041China College of Architecture and Environment Sichuan UniversityChengdu 610041China

Microscale zero valent iron(mFe^(0))is one of the most potential water pollution remediation materials,but the effective utilization ability of electrons released by mFe^(0)in the reduction of hexavalent chromium(Cr(VI))is not ***,we find the microscale iron-copper(m Fe/Cu)bimetals coated with copper on the surface of mFe^(0)can significantly improve the effective utilization of electrons released by mFe^(0).Electrochemical analysis displays that copper plating on the surface of m Fe/Cu can promote the release the electrons from mFe^(0)and reduce the impedance of mFe^(0).Spin-polarized density functional theory(DFT)calculation reveals that Cu on the surface of m Fe/Cu bimetals promotes the release of electrons from mFe^(0)and reduces the adsorption energy of Fe to *** the electron transporter,moreover,Cu can always attract Cr to the hollow position near itself of the Fe surface,which could promote the effective utilization of electrons released by *** utilization ability of electrons in m Fe/Cu system is 12.5 times higher than that in mFe^(0)*** findings provide another basis for the efficient reduction of Cr(VI)by m Fe/Cu bimetals,which could promote the application and popularization of m Fe/Cu bimetals.

关键词： Zero valent iron mFe/Cu bimetals Hexavalent chromium Mechanism Elecreons

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Construction of Dynamic Alloy Interfaces for Uniform Li Deposition in Li-Metal Batteries

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Energy & Environmental Materials 2024年第3期7卷 64-71页

作者： Qingwen Li yulu liu Ziheng Zhang Jinjie Chen Zelong Yang Qibo Deng Alexander V.Mumyatov Pavel A.Troshin Guang He Ning Hu Tianjin Key Laboratory of Advanced Functional Porous Materials Institute for New Energy Materials and Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China Tianneng Co.Ltd Huzhou 313100China Key Laboratory of Hebei Province on Scale-span Intelligent Equipment Technology Tianjin Key Laboratory of Power Transmission and Safety Technology for New Energy Vehiclesand School of Mechanical EngineeringHebei University of TechnologyTianjin 300401China Federal Research Center for Problems of Chemical Physics and Medicinal Chemistry Academician Semenov ave.1Chernogolovka Moscow Region 142432Russia Zhengzhou Research Institute of HIT 26 Longyuan East 7thJinshui DistrictZhengzhou 450000Henan Province China Harbin Institute of Technology 92 West Dazhi StreetNan Gang DistrictHarbin 150001China

It is well accepted that a lithiophilic interface can effectively regulate Li deposition behaviors,but the influence of the lithiophilic interface is gradually diminished upon continuous Li deposition that completely isolates Li from the lithiophilic ***,we perform in-depth studies on the creation of dynamic alloy interfaces upon Li deposition,arising from the exceptionally high diffusion coefficient of Hg in the amalgam solid *** a comparison,other metals such as Au,Ag,and Zn have typical diffusion coefficients of 10-20 orders of magnitude lower than that of Hg in the similar solid solution *** difference induces compact Li deposition pattern with an amalgam substrate even with a high areal capacity of 55 mAh cm^(-2).This finding provides new insight into the rational design of Li anode substrate for the stable cycling of Li metal batteries.

关键词： diffusion coefficient dynamic alloy interfaces Li dendrites Li solid solution uniform Li deposition

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Evaluation of the metabolism of PEP06,an endostatin-RGDRGD 30-amino-acid polypeptide and a promising novel drug for targeting tumor cells

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Journal of Pharmaceutical Analysis 2022年第5期12卷 766-773页

作者： Liyun Niu Huiyu Zhou Yueru Lian Ya Gao yulu liu Ruolan Gu Zhuona Wu Xiaoxia Zhu Hui Gan Zhiyun Meng Guifang Dou State Key Laboratory of Drug Metabolism and Pharmacokinetics Department of Pharmaceutical SciencesBeijing Institute of Radiation MedicineBeijing100850China Henan University KaifengHenan475004China

PEP06 is a novel endostatin-Arg-Gly-Asp-Arg-Gly-Asp(RGDRGD)30-amino-acid polypeptide featuring a terminally fused RGDRGD hexapeptide at the N *** active endostatin fragment of PEP06 directly targets tumor cells and exerts an antitumoral ***,little is known about the kinetics and degradation products of PEP06 in vitro or in *** this study,we investigated the in vitro metabolic stability of PEP06 after it was incubated with living cells obtained from animals of different species;we further identified the degradation characteristics of its cleavage ***06 underwent rapid enzymatic degradation in multiple types of living cells,and the liver,kidney,and blood play important roles in the metabolism and clearance of the peptides resulting from the molecular degradation of *** identified metabolites of PEP06 using full-scan mass spectrometry(MS)and tandem MS(MS2),wherein 43 metabolites were characterized and identified as the degradation metabolites from the parent peptide,formed by successive losses of amino *** metabolites were C and N terminal truncated products of *** structures of 11 metabolites(M6,M7,M16,M17,M21,M25,M33,M34,M39,M40,and M42)were further confirmed by comparing the retention times of similar full MS spectrum and MS2 spectrum information with reference standards for the synthesized *** have demonstrated the metabolic stability of PEP06 in vitro and identified a series of potentially bioactive downstream metabolites of PEP06,which can support further drug research.

关键词： PEP06 HRMS Metabolic stability Metabolites identification

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Spatial statistics of atmospheric particulate matter in China

Spatial statistics of atmospheric particulate matter in Chin...

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第十五届现代数学和力学学术会议

作者： yulu liu Shenghui Gao Zhiming Lu Quan Zhou Yongxiang Huang Shanghai Institute of Applied Mathematics and Mechanics Shanghai University State Key Lab.of Marine Environmental Science College of Ocean and Earth SciencesXiamen University

In recent decades,many cities in China have experienced heavy air pollution episodes leading to negative impacts on human health and the air pollution have been one of the biggest problems in urban areas of many megac...

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设置消能伸臂的高层建筑结构地震反应控制研究

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建筑结构学报 2020年第S02期41卷 86-95页

作者：刘裕禄魏树利王建哈尔滨工业大学土木工程学院黑龙江哈尔滨150090 哈尔滨工业大学结构工程灾变与控制教育部重点实验室黑龙江哈尔滨150090 哈尔滨工业大学(深圳)土木与环境工程学院广东深圳518055

由于高层建筑自身的加速度放大效应,地震作用下其顶部加速度反应易超出相关规范的限值。过大的加速度反应不仅会造成建筑内物品损坏,同时严重影响居住舒适性。为研究高层建筑顶部加速度特性及相应的控制策略,针对设置消能伸臂体系的高... 详细信息

由于高层建筑自身的加速度放大效应,地震作用下其顶部加速度反应易超出相关规范的限值。过大的加速度反应不仅会造成建筑内物品损坏,同时严重影响居住舒适性。为研究高层建筑顶部加速度特性及相应的控制策略,针对设置消能伸臂体系的高层建筑结构,首先根据欧拉梁理论建立结构在地震激励下的振动方程;然后基于随机地震响应分析阻尼器刚度系数和阻尼系数对结构顶部响应的影响;最后运用考虑加速度影响的LQR-accel算法对结构进行主动控制分析。结果表明:以控制顶部加速度响应为目标时,阻尼器存在最优阻尼系数,其刚度系数则越小越有利,结构顶部加速度的降低幅度约为30%;主动控制可以大幅降低体系顶部加速度响应,但是最优主动控制力中被动力占比不高,仅为55.64%。

关键词：高层建筑消能伸臂体系顶部加速度控制随机地震响应 LQR-accel算法减震效果

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Therapeutic potential of bright light therapy for the non-motor symptoms in Parkinson's disease

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Chinese Medical Journal 2022年第2期135卷 243-244页

作者： Yun Shen Siyi Gong yulu liu Jie Li Kangping Xiong Chengjie Mao Yali Wang Dan Li Fen Wang Hua Hu Chunfeng liu Department of Neurology Suzhou Clinical Research Center of Neurological DiseaseThe Second Affiliated Hospital of Soochow UniversitySuzhouJiangsu 215004China Jiangsu Key Laboratory of Neuropsychiatric Diseases Institute of NeuroscienceSoochow UniversitySuzhouJiangsu 215123China Department of Neurology Suzhou Municipal Hospital of Nanjing Medical UniversitySuzhouJiangsu 215008China Department of Neurology Suqian First HospitalSuqianJiangsu 223899China

To the Editor:Alterations of circadian rhythms seem to be the casual contribution to sleep disturbances,depression,and other non-motor symptoms in Parkinson's disease(PD).[1,2]By restoring the circadian rhythm,bright light therapy(BLT)might be a potentially new treatment option for ***,no studies have conclusively demonstrated the effects of BLT on the non-motor symptoms in PD.

关键词： symptoms therapy Therapeutic

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