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Flow instability of supercritical hydrocarbon fuel in a multi-channel cooling system

Chinese Journal of Aeronautics 2024年第2期37卷 283-295页

作者： yichao jin Kun WU Xuejun FAN Institute of Applied Physics and Computational Mathematics Beijing 100094China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Thermally-induced flow instabilities are a critical issue in multi-channel regenerative cooling systems.In particular,the interactions between Density-Wave Oscillations(DWO)and Flow Maldistribution(FMD)can result in complex and disastrous instability phenomena.This study investigates the instability behaviors of hydrocarbon fluid in a four-channel system with a constant heat flux ratio using both frequency-and time-domain methods.As the heat flux increases,the in-tube flow sequentially destabilizes in each channel and converges to new equilibrium states,leading to the emergence of FMD phenomena.This also causes the system eigenvalue to change repeatedly from negative to positive rather than increasing monotonically.Additionally,the system eigenvalues are between those of the two most unstable channels,indicating that the stability behavior of the entire system is dictated by the most unstable channel.After FMD occurs,flow oscillations are activated in channels with weak stability,and the in-tube flow is observed to evolve into various flow patterns,including stable flow,self-sustained oscillation,oscillation divergence,quasiperiodic oscillation,and oscillation excursion.The novel instability mode of oscillation excursion involves a spontaneous transition of operating states.It oscillates from an equilibrium state and then stabilizes at a new operational state after oscillation-induced redistribution.However,the newfound stable state may also be only temporary,with the in-tube flow regressing to the initial state,resulting in quasi-periodic oscillation.

关键词： Cooling Supercritical fluids Hydrocarbons Flow instability Flow maldistribution Density-wave oscillations

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TCMFVis:A visual analytics system toward bridging together traditional Chinese medicine and modern medicine

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Visual Informatics 2023年第1期7卷 41-55页

作者： yichao jin Fuli Zhu Jianhua Li Lei Ma School of Information Science and Engineering East China University of Science and TechnologyMeilong Road 130ShanghaiChina Shanghai Key Laboratory of New Drug Design School of PharmacyEast China University of Science and TechnologyMeilong Road 130ShanghaiChina

Although traditional Chinese medicine(TCM)and modern medicine(MM)have considerably different treatment philosophies,they both make important contributions to human health care.TCM physicians usually treat diseases using TCM formula(TCMF),which is a combination of specific herbs,based on the holistic philosophy of TCM,whereas MM physicians treat diseases using chemical drugs that interact with specific biological molecules.The difference between the holistic view of TCM and the atomistic view of MM hinders their combination.Tools that are able to bridge together TCM and MM are essential for promoting the combination of these disciplines.In this paper,we present TCMFVis,a visual analytics system that would help domain experts explore the potential use of TCMFs in MM at the molecular level.TCMFVis deals with two significant challenges,namely,(i)intuitively obtaining valuable insights from heterogeneous data involved in TCMFs and(ii)efficiently identifying the common features among a cluster of TCMFs.In this study,a four-level(herb-ingredient-targetdisease)visual analytics framework was designed to facilitate the analysis of heterogeneous data in a proper workflow.Several set visualization techniques were first introduced into the system to facilitate the identification of common features among TCMFs.Case studies on two groups of TCMFs clustered by function were conducted by domain experts to evaluate TCMFVis.The results of these case studies demonstrate the usability and scalability of the system.

关键词： Traditional Chinese medicine Visual analytics Set visualization Molecular mechanism

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超临界碳氢燃料流动不稳定的频域分析与数值模拟

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推进技术 2024年第1期45卷 165-173页

作者：靳一超吴坤陆阳范学军北京应用物理与计算数学研究所北京100094 中国科学院力学研究所高温气体动力学国家重点实验室北京100190 中国科学院大学工程科学学院北京100049

再生冷却通道中的流动失稳是高超声速飞行器发动机热防护技术中的核心问题之一。为研究超临界碳氢燃料在冷却通道中的流动不稳定特性,基于有限体积法及流体物性近似,发展了高效的一维瞬态模拟方法;同时,基于小扰动假设,进一步提出了用... 详细信息

再生冷却通道中的流动失稳是高超声速飞行器发动机热防护技术中的核心问题之一。为研究超临界碳氢燃料在冷却通道中的流动不稳定特性,基于有限体积法及流体物性近似,发展了高效的一维瞬态模拟方法;同时,基于小扰动假设,进一步提出了用于预测稳定行为的频域分析方法。通过相关实验,验证了模型的可靠性。基于时域和频域方法的综合分析,沿内特征曲线讨论了主要失稳类型,重点分析了受密度波及Ledinegg不稳定共同影响的复合不稳定性。随后,进一步分析了工作压力和入口温度对稳定特性的耦合影响,并基于N_(tpc)-N_(spc)空间划分了稳定区域。研究发现,复合不稳定、Ledinegg不稳定以及密度波不稳定,随入口温度升高而相继消失。Ledinegg不稳定及密度波不稳定的稳定边界在N_(tpc)-N_(spc)空间具有高度相似性,而复合不稳定性的区域在较高的压力下略有缩小。

关键词：再生冷却热防护碳氢燃料超临界流体流动不稳定瞬态模拟频域分析

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Agent-Oriented Architecture for Ubiquitous Computing in Smart Hyperspace

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Wireless Sensor Network 2010年第1期2卷 74-84页

作者： yichao jin Ruchuan WANG Haiping HUANG Lijuan SUN 不详

Agent-oriented approach is increasingly showing its magic power in a diversity of fields, specifically, ubiquitous computing and smart environment. Meanwhile, it is considered the next creative issue is to interconnect and integrate isolated smart spaces in real world together into a higher level space known as a hyperspace. In this paper, an agent-oriented architecture, which involves the techniques of mobile agents, middleware, and embedded artificial intelligence, is proposed. Detailed implementations describe our efforts on the design of terminal device, user interface, agents, and AI

关键词： Agent-Oriented Ubiquitous Computing Smart Hyperspace Middleware Embedded Artificial Intelligence

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A General Simulation Method for Complex Deformation of Irregular-Shaped Origami Configurations

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Acta Mechanica Solida Sinica 2024年第1期37卷 90-98页

作者： Zhaochen Dong yichao Zhu Xu Guo State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian 116023China

Most existing treatments for origami-folding simulations have focused on regular-shaped configurations.This article aims to introduce a general strategy for simulating and analyzing the deformation process of irregular shapes by means of computational capabilities nowadays.To better simulate origami deformation with folding orders,the concept of plane follow-up is introduced to achieve automated computer simulation of complex folding patterns,thereby avoiding intersection and penetration between planes.Based on the evaluation criteria such as the lowest storage energy with tightening and the fastest pace from tightening to unfolding,the optimal crease distribution patterns for four irregular(‘N’-,‘T’-,‘O’-,and‘P’-shaped)origami configurations are then presented under five candidates.When the dimensions of the origami are fixed,it is discovered that simpler folding patterns lead to faster deformation of the origami configuration.When the folding complexity is fixed,higher strain energy results in more rapid origami expansion.

关键词： Irregular-shaped origami Complex deformation Computer-aided origami design General simulation

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Symbology of Feynman integrals from twistor geometries

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 44-59页

作者： Song He Jiahao Liu yichao Tang Qinglin Yang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China International Centre for Theoretical Physics Asia-Pacific Beijing 100049 Peng Huanwu Center for Fundamental Theory Hefei 230026China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We study the symbology of planar Feynman integrals in dimensional regularization by considering geometric configurations in momentum twistor space corresponding to their leading singularities(LS). Cutting propagators in momentum twistor space amounts to intersecting lines associated with loop and external dual momenta, including the special line associated with the point at infinity, which breaks dual conformal symmetry. We show that cross-ratios of intersection points on these lines, especially those on the infinity line, naturally produce symbol letters for Feynman integrals in D = 4-2∈, which include and generalize their LS. At one loop, we obtain all symbol letters using intersection points from quadruple cuts for integrals up to pentagon kinematics with two massive corners, which agree perfectly with canonical differential equation(CDE) results. We then obtain all two-loop letters, for up to four-mass box and one-mass pentagon kinematics, by considering more intersections arising from two-loop cuts. Finally we comment on how cluster algebras appear from this construction, and importantly how we may extend the method to non-planar integrals.

关键词： Feynman integrals symbol letters twistor geometry

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Continuous preparation of strong and tough PVA nanocomposite fibers by mechanical stretching-assisted salting-out treatment

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Nano Research 2024年第4期17卷 3156-3163页

作者： Hang Chen Guangze Yang Yingzhi Sun yichao Xu Mingjie Liu Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education School of ChemistryBeihang UniversityBeijing 100191China Research Institute for Frontier Science Beihang UniversityBeijing 100191China International Research Institute for Multidisciplinary Science Beihang UniversityBeijing 100191China

Polymer composite fibers with superior properties such as excellent combined strength and toughness and biocompatibility can be used in high-tech applications of braided protective devices and smart wearable,however the research of high-performance polymer composite fiber remains in the infant stage.Here we present a strategy to produce strong and tough anisotropic polymer nanocomposite fibers with orientedly aligned salt rods using mechanical stretching-assisted salting-out treatment.The prepared nanocomposite fibers have a tensile strength of up to 786±2.7 MPa and an elongation at break of 81%,and the anisotropic fibers exhibit good transmission of mechanical vibration in the longitudinal direction with high resolution.During the fabrication process,the salt builds up into oriented rods during the directional salting process,and the polymer is confined to the 150 nm domain between the rods after the solvent is completely evaporated,giving the nanocomposite fibers superior mechanical properties.The presented strategy can be applied to the continuous mass production of nanocomposite fibers and is also generalizable to other polymer nanocomposites,which could extend the applicability of nanocomposite fibers to conditions involving more demanding mechanical loading and mechanical vibration transmission.

关键词： poly(vinyl alcohol)(PVA)nanofibers oriented structure ultrastrong and stiff mechanical vibration transmission salting out continuous production

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基于主动射流控制的高超声速进气道再起动性能研究

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Transactions of Nanjing University of Aeronautics and Astronautics 2022年第6期39卷 651-662页

作者：靳一超姚卫北京应用物理与计算数学研究所北京100094 中国科学院力学研究所高温气体动力学国家重点实验室北京100190 中国科学院大学工程科学学院北京100049

基于主动射流技术,本文提出了一种应用于高超声速进气道再起动的控制方法。采用URANS(Unsteady Reynolds averaged Navier-Stokes)方法对再起动的动态过程进行了数值模拟,验证了控制方法的有效性,并揭示了射流条件的影响。主动射流将高... 详细信息

基于主动射流技术,本文提出了一种应用于高超声速进气道再起动的控制方法。采用URANS(Unsteady Reynolds averaged Navier-Stokes)方法对再起动的动态过程进行了数值模拟,验证了控制方法的有效性,并揭示了射流条件的影响。主动射流将高压分离泡从内缩段转移至上游并充分膨胀,缓解了内缩段的逆压梯度,从而改善了进气道的不起动状态。关闭射流后,进气道在射流膨胀诱导的顺压环境中成功实现再起动。接着,分析了射流动量比的影响以指导射流控制方法的设计并选择合适的动量比。较低的射流动量不足以消除高压分离泡,而过大的射流动量则会诱导较强的弓形激波并造成严重的动量损失。移除射流后,将在下壁面形成较厚的低速层,使进气道回退为不起动状态。因此,使用主动射流辅助进气道再起动的一般原则为确保射流在出口下游充分膨胀,同时避免在上游造成较大的动量损失,并防止形成较厚的低速层。

关键词：高超声速进气道不起动再起动主动射流流动控制

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Remarkable enhancement of gas selectivity on organosilica hybrid membranes using urea-modulated metal-organic framework nanoparticles

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 83-92页

作者： Yayun Zhao Dechuan Zhao Chunlong Kong yichao Lin Xuezhen Wang Liang Chen Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China Collaboration Innovation Center for Tissue Repair Material Engineering Technology China West Normal UniversityNanchong 637009China

Metal-organic framework/organosilica hybrid membranes on tubular ceramic substrates have shown great potential for the implementation of membrane technology in practical gas separation projects due to their higher permeance compared to commercial polymers.However,the selectivities of the reported membranes are moderate.Here,we have incorporated urea-modulated metal-organic frameworks into organosilica membranes to greatly enhance its separation performance.The urea-modulated metal-organic frameworks exhibit less-defined edges of crystallographic facets and high defect density.They can be well-dispersed in the organosilica layer,which substantially suppresses the interfacial defects between metal-organic frameworks and organosilica,which is beneficial for improving the selectivity of membranes for gas separation.The results have shown that the enhanced ideal selectivity of H_(2)/CH_(4) was 165 and that of CO_(2)/CH_(4) was 43,with H_(2) permeance of about 1.25×10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) and CO_(2) permeance of 3.27×10^(−7) mol·m^(−2)·s^(−1)·Pa^(−1) at 0.2 MPa and 25℃.In conclusion,the high level of hybrid membranes can be used to separate H_(2)(or CO_(2))from the binary gas mixture H_(2)/CH_(4)(or CO_(2)/CH_(4)),which is important for gas separation in practical applications.Moreover,the simple and feasible modulation of metal-organic framework is a promising strategy to tune different metal-organic frameworks for membranes according to the actual demands.

关键词： ZIF-8 nanocrystals urea organosilica hybrid membrane enhanced separation performance

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Effects of long-term fencing on soil microbial community structure and function in the desert steppe,China

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Journal of Arid Land 2024年第3期16卷 431-446页

作者： PAN Yaqing KANG Peng QU Xuan RAN yichao LI Xinrong Shapotou Desert Research and Experiment Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China School of Biological Science and Engineering North Minzu UniversityYinchuan 750021China

One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this study,we investigated the diversity and aboveground biomass of Caragana korshinskii Kom.shrub communities in long-term fencing and grazing areas,combined with an analysis of soil physical-chemical properties and genomics,with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe,China.The results showed that fence management(exclosure)increased plant diversity and aboveground biomass in C.korshinskii shrub area and effectively enhanced soil organic carbon(233.94%),available nitrogen(87.77%),and available phosphorus(53.67%)contents.As well,the Shannon indices of soil bacteria and fungi were greater in the fenced plot.Plant-soil changes profoundly affected the alpha-and beta-diversity of soil bacteria.Fence management also altered the soil microbial community structure,significantly increasing the relative abundances of Acidobacteriota(5.31%-8.99%),Chloroflexi(3.99%-5.58%),and Glomeromycota(1.37%-3.28%).The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity.Based on functional predictions,fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions.The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and saprotrophs also significantly increased under fence management.In addition,the differential functional groups of bacteria and fungi were closely related to plant-soil changes.The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.

关键词： desert steppe fence management Caragana korshinskii soil physical-chemical property soil microorganism

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