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Alignment of inertialess spheroidal particles in flow-structure-dominated regions of turbulent channel flow:shape effect

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Acta Mechanica Sinica 2024年第8期40卷 45-66页

作者： Zhiwen Cui lihao Zhao Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing100084China Laboratory of Flexible Electronics Technology Tsinghua UniversityBeijing100084China

The alignment of elongated fibers and thin disks is known to be significantly influenced by the presence of fluid coherent structures in near-wall turbulence(Cui et al.2021).However,this earlier study is confined to the spheroids with infinitely large or small aspect ratio,and the shape effect of finite aspect ratio on the alignment is not *** current study investigates the shape-dependent alignment of inertialess spheroids in structure-dominated regions of channel *** utilizing an ensemble-averaged approach for identifying the structure-dominated regions,we analyze the eigensystem of the linear term matrix in the Jeffery equation,which is governed by both particle shape and local fluid velocity *** contrast to earlier conventional analysis based on local vorticity and strain rate,our findings demonstrate that the eigensystem of the Jeffery equation offers a convenient,effective,and universal framework for predicting the alignment behavior of inertialess spheroids in turbulent *** leveraging the eigensystem of the Jeffery equation,we uncover a diverse effect of fluid coherent structures on spheroid alignment with different particle ***,we provide explanations for both shape-independent alignments observed in vortical-core regions and shape-dependent alignments around near-wall streamwise vortices.

关键词： Non-spherical particle Direct numerical simulation Wall turbulence Particle-laden flow

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 85-99页

作者： Xu, Buxian Hu, Dongping Feng, lihao Beihang Univ Fluid Mech Key Lab Minist Educ Beijing 100191 Peoples R China Dongfang Turbine Co Ltd State Key Lab Clean & Efficient Turbomachinery Pow Dongfang Elect Corp Deyang 618000 Peoples R China

Thrust vectoring technology plays an important role in improving the maneuverability of aircraft. In order to overcome the disadvantages of mechanical thrust vectoring nozzles, such as complications of structure and significant increases in weight and cost, fluidic thrust vectoring nozzles are proposed. Dual Throat fluidic thrust vectoring Nozzle (DTN) has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss. In this study, three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response. Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated. It is found that the dynamic response will experience three stages: rapid-deflecting stage, oscillating stage, and steady stage. A complete recirculation zone forms at the end of the rapid-deflecting stage, which pushes the primary flow to attach to the wall opposite the secondary injection. Meanwhile, the exhaust flow is deflected. In terms of DTN's application, the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers. In addition, continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios. The control moment is generated due to the asymmetrical pressure distribution of nozzle surface, which is mainly contributed by the pressure decrease on the secondary injection surface. Moreover, the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5 degrees/% and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4. These results provide an important theoretical basis for the practical application of DTN. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommo

关键词： Dual throat nozzle Dynamic response characteristic Flow control Flying-wing aircraft

Rheological study of methane gas hydrates in the presence of micron-sized sand particles

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Chinese Journal of Chemical Engineering 2024年第6期70卷 149-161页

作者： Bohui Shi Shangfei Song Yuchuan Chen Shunkang Fu lihao Liu Xinyao yang Haihao Wu Guangjin Chen Jing Gong National Engineering Research Center of Oil and Gas Pipeline Transportation Safety MOE Key Laboratory of Petroleum EngineeringBeijing Key Laboratory of Urban Oil and Gas Distribution TechnologyChina University of Petroleum-BeijingBeijing 102249China China's Oil and Gas Exploration and Development Company(CNODC) Beijing 100034China China National Petroleum Corporation Mozambique LDA MaputoMozambique PipeChina West East Pipeline Company Shanghai 200122China

Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy ***,their commercial exploitation faces challenges,particularly operational disruptions caused by sand-related *** the rheological properties of hydrate slurry,especially in the presence of micron-sized sand particles,is imperative for ensuring the flow assurance of subsea hydrate *** study extensively investigates the rheological properties of sand-containing hydrate *** findings reveal that these slurries exhibit non-Newtonian fluid characteristics,including yield stress,thixotropy,and shear-thinning ***-like elastic features are observed in sand-containing hydrate slurries before yielding,transitioning to viscous behavior after *** with a minimal amount of sand,both static yield stress and yield strain experience substantial changes,correlating with the increase in sand *** research conclusively establishes the thixotropic nature of sand-hydrate slurries,where the viscosity decay rate is directly influenced by the shear *** insights aim to contribute comprehensively to the development of effective flow assurance strategies,ensuring the safe and stable operation of subsea hydrate exploitation.

关键词： Natural gas hydrate production Sand-containing hydrate slurries Yield stress Thixotropy Shear-thinning behavior

Enhancing Geological Understanding and Identifying Gold Anomalies in the Ailaoshan Orogen

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 441-453页

作者： ZHAO Shiyu yang Lin SONG Yiwei DONG Yuntao FENG lihao LI Huajian WU Junyu WANG Qingfei State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Xi’an Center of Mineral Resources Survey China Geological SurveyXi’an 710010China Yunnan Gold Mining Industry Group Kunming 650299China Jiangxi Provincial Key Laboratory of Genesis and Prospect for Strategic Minerals East China University of TechnologyNanchang 330013China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China

The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental *** elements can conceal or reduce anomalies due to the mutual effect between different anomaly *** the whole zone into subzones based on tectonic settings,ore cluster areas,or sample catchment basins(Scb),geochemical and structural anomalies associated with gold(Au)mineralization have been identified utilizing mean plus twice standard deviations(Mean+2STD),factor analysis(FA),concentration-area(CA)modeling of stream sediment geochemical data,and lineament density in both the Ailaoshan Orogen and the individual *** FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types,identify specific element associations of known rocks and discern the porphyry or skarn-type Au *** with methods of Mean+2STD and C-A model of data in the whole orogen,which mistake the anomalies as background or act the background as anomalies,the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential *** of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament *** contrast,the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density,consistent with the locations of known Au *** analyzing the map of faults and Au anomalies,two potential prospecting targets,Scbs 1 and 63 with a sandstone as a potential host rock for Au,have been identified in the Ailaoshan *** use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying

关键词： minerology geochemistry gold stream sediment sample catchment basin concentration-area model lineament density Ailaoshan Orogen

A distinction of gliomas at cellular and tissue level by surface-enhanced Raman scattering spectroscopy

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Chinese Chemical Letters 2024年第5期35卷 423-427页

作者： Chengde Wang Liping Huang Shanshan Wang lihao Wu Yi Wang Jun Dong Department of Neurosurgery The Second Affiliated Hospital of Soochow UniversitySuzhou 215004China Department of Neurosurgery The First Affiliated Hospital of Wenzhou Medical UniversityWenzhou 325000China School of Ophthalmology and Optometry Eye HospitalSchool of Biomedical EngineeringWenzhou Medical UniversityWenzhou 325001China Department of Chemistry School of Science and Research Center for Industries of the FutureWestlake UniversityHangzhou 310030China

Glioblastoma multiforme(GBM)is the most common malignant primary brain tumor in *** precise identification and distinction of GBM heterogeneity from surrounding brain parenchyma at the cellular level and even at the tissue level are important for GBM *** this study,GBM cells are distinguished from normal astrocytes and non-central nervous system(CNS)tumor cells by surface-enhanced Raman scattering(SERS)based on gold nanoshell(SiO_(2)@Au)particles and support vector machine(SVM)*** addition,the gold nanoisland(AuNI)SERS substrates are further developed and explored for accurate detection of GBM at the tissue *** distinction between glioma and trauma tissues,identification of different tumor grades,and IDH mutation are realized with the assistance of orthogonal partial least squares discriminant analysis(OPLS-DA)in a rapid,non-invasive,and convenient *** results show that the developed SERS-based analytical method has the potential for practical application for the detection of GBM at the single-cell and tissue levels and even for real-time intraoperative diagnosis.

关键词： Glioblastoma multiforme(GBM) Surface-enhanced Raman scattering(SERS) Nanoparticle Nanoisland Machine learning

Introducing cerium into TiO_(2)@MnO_(x) hollow-sphere structure for highly active photothermocatalysis degradation of ethyl acetate and NO under H_(2)O at low temperature

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Journal of Rare Earths 2024年第5期42卷 889-898,I0003页

作者： Yinming Fan Yanhong Wang Morui Li Yinian Zhu Zongqiang Zhu Shengpeng Mo lihao Zhang Shen Tang Xiaobin Zhou Yanping Zhang Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area Guilin University of TechnologyGuilin541004China The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control.Guilin University of Technology.Guilin 541004China Technical Innovation Center of Mine Geological Environmental Restoration Engineering in Southern Karst Area Nanning530022China

The CeO_(2)-TiO_(2)@MnO_(x) catalyst was prepared by the co-precipitation method and applied to the photothermocatalysis system of ethyl acetate and NO simultaneous degradation under H_(2)O at low temperature,which introduced Ce into TiO_(2)@MnO_(x) hollow sptrera *** optimum TiO_(2)/MnO_(x) ratio and Ce introducing amount were obtained in the *** of them,the NO and ethyl acetate conversion percentage of TiO_(2)@MnO_(x)(n_(Mn):n_(Ti)=40:40)is 74%and 62%at 240℃,***_(2)-TiO_(2)@MnO_(x)(n_(Mn):n_(Ce)=1:1)exhibits the best catalytic performance,its efficiency for NO conversion is 83%and the conversion of ethyl acetate reaches 72%at 240℃.In addition,it is confirmed that the Cedoped nanocomposites have more uniform dispersion through various characterization and analysis ***,these catalysts have a large specific surface area as well as a large number of surface-active oxygen and oxygen *** can further improve the catalytic performance based on the adjusted ratio of active ***,this work investigated the relationship between multi-metal interactions and catalytic performance in the presence of H_(2)***,the possible reaction pathways for the simultaneous removal of NO and ethyl acetate were explored in our system.

关键词： Photothermocatalysis Ethyl acetate NO Low temperature H_(2)O Rare earths

Review on the terahertz metasensor:from featureless refractive index sensing to molecular identification

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Photonics Research 2024年第2期12卷 194-217页

作者： JIAMING LYU lihao HUANG LIN CHEN YIMING ZHU SONGLIN ZHUANG THz Technology Innovation Research Institute Shanghai Key Laboratory of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 200092China

The terahertz(THz)wave is at the intersection between photonics and electronics in the electromagnetic *** the vibration mode of many biomedical molecules and the weak interaction mode inside the molecules fall in the THz regime,utilizing THz radiation as a signal source to operate substance information sensing has its unique ***,the metamaterial sensor(metasensor)has greatly enhanced the interaction between signal and substances and spectral selectivity on the subwavelength ***,most past review articles have demonstrated the THz metasensor in terms of their structures,applications,or *** recently,with the rapid development of metasensing technologies,the molecular information has paid much more attention to the platform of THz *** this review,we comprehensively introduce the THz metasensor for detecting not only the featureless refractive index but also the vibrational/chiral molecular information of *** objectives of this review are to improve metasensing specificity either by chemical material-assisted analyte capture or by physical molecular ***,to boost THz absorption features in a certain frequency,the resonant responses of metasensors can be tuned to the molecular vibrational modes of target molecules,while frequency multiplexing techniques are reviewed to enhance broadband THz spectroscopic *** chiral metasensors are also summarized to specific identification chiral ***,the potential prospects of next generation THz metasensors are *** to featureless refractive index metasensing,the specific metasensor platforms accelerated by material modification and molecular information will lead to greater impact in the advancement of trace detection of conformational dynamics of biomolecules in practical applications.

关键词： refractive index sensor

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基于差分隐私机制的位置数据隐私保护策略

计算机应用研究 2018年第3期35卷 895-900页

作者：杨理皓谷科李威长沙理工大学计算机与通信工程学院综合交通运输大数据智能处理湖南省重点实验室长沙410114

位置定位服务技术作为一种全新的移动计算服务,在日常生活中应用广泛。一方面,数据信息共享极大地方便了人们的日常生活,另一方面也存在由于泄露个人敏感信息而产生的弊端,因此如何保护好位置数据是关键。由于位置数据具有价值高和低密... 详细信息

位置定位服务技术作为一种全新的移动计算服务,在日常生活中应用广泛。一方面,数据信息共享极大地方便了人们的日常生活,另一方面也存在由于泄露个人敏感信息而产生的弊端,因此如何保护好位置数据是关键。由于位置数据具有价值高和低密度的特性,导致现有的隐私保护方法很难兼顾数据的保护和数据的效用性。基于差分隐私机制的位置数据隐私保护策略通过采用多级查询树的结构来查询和发布保护后的数据,并保持了数据项间的联系。首先构建多级查询树(位置搜索树),然后遍历查询树,使用差分隐私的指数机制来选取访问频率高的k项,最后通过拉普拉斯机制给选取的k项进行加噪。实验表明,相比于其他保护策略,基于差分隐私机制的位置数据隐私保护策略可用性和数据保护程度高,算法运行时间少,效率更高。

关键词：位置数据访问频率差分隐私保护多级查询树

Detection of UAV Target Based on Continuous Radon Transform and Matched Filtering Process for Passive Bistatic Radar

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Journal of Beijing Institute of Technology 2024年第1期33卷 9-18页

作者： Luo Zuo Yuefei Yan Jun Wang Xin Sang Yan Wang Dongming Ge lihao Ping Zhihai Wang Congsi Wang Guangzhou Institute of Technology Xidian UniversityGuangzhou 510555China National Laboratory of Radar Signal Processing Xidian UniversityXi’an710071China School of Information and Control Engineering Xi’an University of Architecture and TechnologyXi’anShaanxi 710055China CETC Wuhu Diamond Aircraft Manufacturing Co. LtdWuhuAnhui 241000China Beijing Space Vehicle General Design Department Beijing 100094China CETC No.38 Research Institute Hefei 230088China

Long-time integration technique is an effective way of improving target detection performance for unmanned aerial vehicle(UAV)in the passive bistatic radar(PBR),while range migration(RM)and Doppler frequency migration(DFM)may have a major effect due to the target *** paper proposed an innovative long-time coherent integration approach,regarded as Continuous Radon-matched filtering process(CRMFP),for low-observable UAV target in passive bistatic *** not only mitigates the RM by collaborative research in range and velocity dimensions but also compensates the DFM and ensures the coherent integration through the matched filtering process(MFP).Numerical and real-life data following detailed analysis verify that the proposed method can overcome the Doppler mismatch influence and acquire comparable detection performance.

关键词： passive bistatic radar unmanned aerial vehicle long-time coherent integration Radon-matched filtering process