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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 conducted.The 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=100.The mass flow rates of two synthetic jets imposed on different positions of the cylinderθ1andθ2are trained to control the flow.The optimal jet placement that achieves the highest drag reduction is determined for each case.For 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 fluctuation.The control jets elongate the vortex shedding,and reduce the pressure drop.Meanwhile,the flow topology is modified at a high angle of attack.For an ellipse with a relatively higher axis ratio,i.e.,Γ1.6,the drag reduction is achieved for all the angles of attack studied.The larger the angle of attack is,the higher the drag reduction ratio is.The increased fluctuation in the drag coefficient under control is encountered,regardless of the position of the control jets.The control jets modify the flow topology by inducing an external vortex near the wall,causing the drag reduction.The 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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Spatiotemporal variations in ecosystem services and their trade-offs and synergies against the background of the gully control and land consolidation project on the Loess Plateau,China

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Journal of Arid Land 2024年第1期16卷 131-145页

作者： WANG Jing WEI yulu PENG Biao liu Siqi LI Jianfeng Key Laboratory of Degraded and Unused Land Consolidation Engineering Ministry of Natural and ResourcesXi'an 710075China Institute of Land Engineering and Technology Shaanxi Provincial Land Engineering Construction Group Co.Ltd.Xi'an 710021China School of Human Settlements and Civil Engineering Xi'an Jiaotong UniversityXi'an 710049China Shaanxi Key Laboratory of Land Consolidation Xi'an 710064China

Studying the spatiotemporal variations in ecosystem services and their interrelationships on the Loess Plateau against the background of the gully control and land consolidation(GCLC)project has significant implications for ecological protection and quality development of the Yellow River Basin.Therefore,in this study,we took Yan'an City,Shaanxi Province of China,as the study area,selected four typical ecosystem services,including soil conservation service,water yield service,carbon storage service,and habitat quality service,and quantitatively evaluated the spatiotemporal variation characteristics and trade-offs and synergies of ecosystem services from 2010 to 2018 using the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.We also analysed the relationship between the GCLC project and regional ecosystem service changes in various regions(including 1 city,2 districts,and 10 counties)of Yan'an City and proposed a coordinated development strategy between the GCLC project and the ecological environment.The results showed that,from 2010 to 2018,soil conservation service decreased by 7.76%,while the other three ecosystem services changed relatively little,with water yield service increasing by 0.56% and carbon storage service and habitat quality service decreasing by 0.16% and 0.14%,respectively.The ecological environment of Yan'an City developed in a balanced way between 2010 and 2018,and the four ecosystem services showed synergistic relationships,among which the synergistic relationships between soil conservation service and water yield service and between carbon storage service and habitat quality service were significant.The GCLC project had a negative impact on the ecosystem services of Yan'an City,and the impact on carbon storage service was more significant.This study provides a theoretical basis for the scientific evaluation of the ecological benefits of the GCLC project and the realization of a win-win situation between food security and ecological security.

关键词： ecosystem services trade-offs and synergies gully control and land consolidation habitat quality Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model Loess Plateau

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Connecting Calcium-Based Nanomaterials and Cancer:From Diagnosis to Therapy

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Nano-Micro Letters 2022年第9期14卷 95-131页

作者： Shuang Bai yulu Lan Shiying Fu Hongwei Cheng Zhixiang Lu Gang liu State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics Center for Molecular Imaging and Translational MedicineSchool of Public HealthXiamen UniversityXiamen 361102People’s Republic of China State Key Laboratory of Cellular Stress Biology Innovation Center for Cell BiologySchool of Life SciencesXiamen UniversityXiamen 361102

As the indispensable second cellular messenger,calcium signaling is involved in the regulation of almost all physiological processes by activating specific target proteins.The importance of calcium ions(Ca^(2+))makes its“Janus nature”strictly regulated by its concentration.Abnormal regulation of calcium signals may cause some diseases;however,artificial regulation of calcium homeostasis in local lesions may also play a therapeutic role.“Calcium overload,”for example,is characterized by excessive enrichment of intracellular Ca^(2+),which irreversibly switches calcium signaling from“positive regulation”to“reverse destruction,”leading to cell death.However,this undesirable death could be defined as“calcicoptosis”to offer a novel approach for cancer treatment.Indeed,Ca^(2+)is involved in various cancer diagnostic and therapeutic events,including calcium overload-induced calcium homeostasis disorder,calcium channels dysregulation,mitochondrial dysfunction,calcium-associated immunoregulation,cell/vascular/tumor calcification,and calcification-mediated CT imaging.In paral-lel,the development of multifunctional calcium-based nanomaterials(e.g.,calcium phosphate,calcium carbonate,calcium peroxide,and hydroxyapatite)is becoming abundantly available.This review will highlight the latest insights of the calcium-based nanomaterials,explain their application,and provide novel perspective.Identifying and characterizing new patterns of calcium-dependent signaling and exploiting the disease element linkage offer additional translational opportunities for cancer theranostics.

关键词： Calcium-based nanomaterials Cancer therapy Calcium signaling Tumor calcification Theranostics

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Diastereoselective Construction of α-Fluoroalkyl Cycloalkanols via Radical Alkylation of α-Fluoroalkyl Ketones

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Chinese Journal of Chemistry 2023年第23期41卷 3275-3280页

作者： Yi liu Ji Li yulu Zhou Hanliang Zheng Zhenlu Shen Gangguo Zhu Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Department of ChemistryZhejiang Normal University688 Yingbin RoadJinhuaZhejiang321004 China College of Chemical Engineering Zhejiang University of TechnologyHangzhouZhejiang310032 China

α-Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds.As such,it is highly desirable to develop efficient methods for assembling these scaffolds.Herein,a visible-light-induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed,producing a variety of decorate α-Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity.A radical chain mechanism involving an intramolecular radical addition to the α-Rf carbonyl group and a subsequent intermolecular hydrogen atom transfer (HAT) has been proposed.Density functional theory (DFT) calculations indicate that a fluorine effect contributes to the radical addition to carbonyls by lowering the π* (C=O) orbital energy of CORf and energy barrier of the HAT between alkoxy radicals and THF,which may be valuable for controllable transformations of fluorinated molecules.

关键词： Radical reactions Cyclization Alkylation α-Fluoroalkyl ketones Fluorine effect Alcohols

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Cenozoic potassic volcanic rocks from the Keluo and Wudalianchi volcanic districts,northeast China:origin from the new sub-continental lithospheric mantle(SCLM)metasomatized by potassium-rich fluids from delaminated lower crust

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Frontiers of Earth Science 2022年第4期16卷 989-1004页

作者： Fanchao MENG yulu TIAN Yaoqi ZHOU Jiaqi liu Gengchao ZUO Qing DU School of Geosciences China University of Petroleum(East China)Qingdao 266580China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266061China Shandong Provincial Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

A series of Cenozoic potassium-rich volcanic rocks developed in the Xiaoguli-Keluo-Wudalianchi-Erkeshan districts,northeast China.The source region and potassium-rich mechanism of the potassic rocks remain highly disputed.In this paper,the major elements,trace elements,and Sr-Nd-Pb isotopes of the volcanic rocks in Keluo(KL)and Wudalianchi(WDLC)volcanic districts were analyzed systematically.The results show that the volcanic rocks are characterized by high K2O(4.36wt.%-6.13wt.%),remarkable enrichment in LREEs and LILEs,as well as the strong fractionation of HREEs.The isotopic characteristics with high 87Sr/86Sr(0.704990-0.705272),low 143Nd/144Nd(0.512306-0.512417),low 206Pb/204Pb(16.546-17.135)and 207Pb/204Pb(15.002-15.783)of the volcanic rocks suggest the involvement of EM-I-type mantle.On the basis of the geochemical characteristics,the potassium-rich volcanic magma originated from the new SCLM forming after delamination of the ancient SCLM,with metasomatism of the potassium-rich fluids released from the ancient lower crust during the Late Mesozoic.The proposed genetic model assumes the source which represented by a phlogopite-bearing garnet peridotite(with modal garnet in the range of 2%-10%)experienced very low degrees(i.e.,~0.5)of partial melting.During Cenozoic,the lithosphere in northeast China was affected by the extension and decompression of continental rift,and the metasomatized SCLM underwent low degree partial melting,resulting in the formation of potassium-rich primitive basaltic magma.

关键词： northeast China Keluo-Wudalianchi volcanic districts Cenozoic potassic volcanic rocks petrogenesis sub-continental lithospheric mantle

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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 PD.However,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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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 terminus.The active endostatin fragment of PEP06 directly targets tumor cells and exerts an antitumoral effect.However,little is known about the kinetics and degradation products of PEP06 in vitro or in vivo.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 products.PEP06 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 PEP06.We 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 acids.The metabolites were C and N terminal truncated products of PEP06.The 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 metabolites.We 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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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)convection.Direct 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=0.7.First,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 studies.To gain insights into the material transport,LCSs are extracted using the finite-time Lyapunov exponent(FTLE)method.Interestingly,lobe structures are widely present,and we elucidate their role in transporting heat from the corner rolls to large-scale circulation.Next,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 background.Furthermore,we quantify the heat flux along the LCSs,which contributes to about 85%of the total flux regardless of Ra.This suggests that LCSs play a significant role in heat transport.Finally,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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