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Aeroelastic vibration analysis of a 1.5 stage compressor

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Propulsion and Power Research 2020年第1期9卷 26-36页

作者： Yun Zheng qingzhe gao Hui Yang Kang Xu School of Energy and Power Engineering Beihang UniversityBeijing100191China Collaborative Innovation Center for Advanced Aero-Engine Beijing100191China

Aeroelastic vibration problems are commonly found in modern compressors operating in off-design conditions.Large amplitude vibration could lead to high cycle fatigue(HCF)of blade and usually occurs in front stages of axial compressors.In this study,the influence of tip gap size on aeroelastic stability is analyzed in a 1.5 stage compressor with an in-house fluid-structure interaction code.A three-dimensional unstructured finite-volume compressible flow solver is applied in the fluid domain and a structure dynamic solver with the modal superimposition method for blade motion is used in the structure domain.Rotor tip clearances of 1%,2%and 3%of tip axial chord at maximum rotor loading conditions at off-design speeds are analyzed for aeroelastic stability.The tip leakage flow and vortex structure can be seen near the blade tip region at a larger tip gap size.The aeroelastic stability of rotor blade at different tip gap sizes is mainly influenced by the 1st torsion mode,and the variation of aerodynamic damping is not monotonous.The intensity of the tip vortex and shock wave are the key factors affecting the aeroelastic stability of rotor when tip gap size increases.

关键词： Aeroelastic vibration problems Axial compressors Tip gap size Aeroelastic stability Tip vortex Shock wave

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导叶非均匀布局对气动激励的影响

航空动力学报 2022年第11期37卷 2627-2635页

作者：郑赟崔健高庆哲金秀博北京航空航天大学能源与动力工程学院北京100191

导叶非均匀布局是抑制下游转子叶片气动激励的重要方法,对半均分的非均匀布局既能以叶片数为设计参数也能以通道面积为设计参数。推导了对半均分布局下的气动激励理论解,比较了两种设计方案的区别;以某1.5级压气机为例,对比两种非均匀... 详细信息

导叶非均匀布局是抑制下游转子叶片气动激励的重要方法,对半均分的非均匀布局既能以叶片数为设计参数也能以通道面积为设计参数。推导了对半均分布局下的气动激励理论解,比较了两种设计方案的区别;以某1.5级压气机为例,对比两种非均匀方案下的气动激励特性,分析转子叶片表面非定常气动力的频谱特性,探究激励特性与通道面积的关系,揭示对半均分布局气动激励的分频机理。结果表明:导叶叶排通道面积的变化导致气动激励分频,气动激励具有一定传播规律进而影响转子叶片气动响应幅值分布,两种非均匀方案下气动激励的空间分布和频域特征不同,以通道面积为设计参数时能够获得准确的非均匀激励模式。

关键词：导叶非均匀布局对半均分布局设计方法通道面积激励特性

Orthogonal Combinatorial Raman Codes Enable Rapid High-Throughput-Out Library Screening of Cell-Targeting Ligands

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Research 2024年第1期2023卷 199-208页

作者： Yuchen Tang Xingxing Zheng Tingjuan gao China Key Laboratory of Pesticide and Chemical Biology of Ministry of Education College of ChemistryCentral China Normal UniversityWuhan 430079China

High-throughput assays play an important role in the fields of drug discovery,genetic analysis,and clinical diagnostics.Although super-capacity coding strategies may facilitate labeling and detecting large numbers of targets in a single assay,practically,the constructed large-capacity codes have to be decoded with complicated procedures or are lack of survivability under the required reaction conditions.This challenge results in either inaccurate or insufficient decoding outputs.Here,we identified chemical-resistant Raman compounds to build a combinatorial coding system for the high-throughput screening of cell-targeting ligands from a focused 8-mer cyclic peptide library.The accurate in situ decoding results proved the signal,synthetic,and functional orthogonality for this Raman coding strategy.The orthogonal Raman codes allowed for a rapid identification of 63 positive hits at one time,evidencing a high-throughput-out capability in the screening process.We anticipate this orthogonal Raman coding strategy being generalized to enable efficient high-throughput-out screening of more useful ligands for cell targeting and drug discovery.

关键词： enable throughput allowed

Evolution of HIV/AIDS Prevention and Control Policies in China:A Grounded Theory Approach

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China CDC weekly 2024年第1期6卷 12-22页

作者： Huang Li Rui gao Chichen Zhang School of Public Health Southern Medical UniversityGuangzhou CityGuangdong ProvinceChina School of Health Management Southern Medical UniversityGuangzhou CityGuangdong ProvinceChina Key Laboratory of Philosophy and Social Sciences of Colleges and Universities in Guangdong Province for Collaborative Innovation of Health Management Policy and Precision Health Service Southern Medical UniversityGuangzhou CityGuangdong ProvinceChina Graduate School Xi’an Jiaotong-Liverpool UniversitySuzhou CityJiangsu ProvinceChina School of Political Science and Public Administration Soochow UniversitySuzhou CityJiangsu ProvinceChina

Objective:This study aims to provide a theoretical foundation for the development and practical application of human immunodeficiency virus(HIV)/acquired immunodeficiency syndrome(AIDS)prevention and control policy systems in China by scrutinizing,analyzing,and synthesizing the evolution of Chinese policies in this domain.Methods:Utilizing grounded theory,we employed NVivo12 software to perform text content analysis,mining,and coding classification,along with visualization techniques,on policy texts sourced from Chinese government platforms,including the official website of China’s State Council.We considered four analytical dimensions—time,subject,type,and object.Results:The National Health Commission and the State Council emerged as the primary entities engaged in policymaking for HIV/AIDS in China.We identified four distinct stages in the evolution of these policies,culminating in a novel‘sun-shaped’HIV/AIDS prevention and control policy network model with an emphasis on‘knowledge,attitude,and practice’at its nucleus,which aligns with national conditions and societal progress.Furthermore,the focal groups of these policies have been dynamically refined and updated over time.Conclusions:Our findings introduce a‘sunshaped’HIV/AIDS prevention and control policy network model specific to China.We observed a conceptual policy shift towards prioritizing overall human health rather than confining the focus to disease treatment.Additionally,in light of China’s growing elderly population,the imperative to address HIV/AIDS prevention and control among older adults is an issue that warrants increased attention.

关键词： prevention HIV/AIDS policy

Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： Kun gao Yan Peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting process.The effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in detail.In each rotation,the casting wheel passes through four different spray zones.The results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,respectively.The temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

The late Early-Paleozoic granitic magmatism in Northwestern Fujian, China: constraints on intraplate orogeny in the South China block

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Acta Geochimica 2024年第1期43卷 134-149页

作者： WanLi gao ZongXiu Wang Institute of Geomechanics Chinese Academy of Geological ScienceBeijing 100081People’s Republic of China Key Laboratory of Paleomagnetism and Tectonic Reconstruction of Ministry of Natural Resources Beijing 100081People’s Republic of China

The Early Paleozoic tectono-thermal event was a significant orogenic activity during the Phanerozoic era,which had a profound impact on the early crust of the South China Block(SCB) and established the foundation for later tectonic activity.The Wuyi-Yunkai orogenic belt in Southeastern China was extensively exposed to Early Paleozoic magmatism,the genetic mechanism of which remains controversial.To shed light on this issue,detailed petrological,geochemical,and zircon U-Pb-Hf isotopic studies were carried out on two granitoids,namely the Yuntongshan pluton and the gaoqiao pluton,identified in the central Wuyishan.Zircon U-Pb chronology of the Yuntongshan and gaoqiao bodies yielded ages of437±4 Ma(MSWD=2.2) and 404±2 Ma(MSWD=12),respectively,indicating that they were emplaced during the Early Silurian and Early Devonian periods.These granitoids are primarily composed of biotite-granite and biotite-monzonitic-granites,with high concentrations of S_(i)O_(2)(73.59-75.91 wt%),K_(2)O+Na_(2)O(8.31-8.73wt%),and low contents of MgO,CaO,Cr,Ni.They are classified as high-K calc-alkaline and weakly metaluminous-strongly peraluminous S-type granites.These granitoids are enriched in light rare earth elements(LREEs) and large ion lithophile elements(LILEs) and depleted in heavy rare earth elements(HREEs) and high field strength elements(HFSEs) with arc affinity.The εHf(t) values of-3.3 to-15.4 with two-stage Hf model ages ranging from 2829 to 1644 Ma,combined with the presence of Neoproterozoic inherited zircons,suggest that the primary magma of these granitoids was derived from the partial melting of Neoproterozoic crust with a Paleoproterozoic crustal model age.These findings,combined with the spatio-temporal distribution of regional magmatism,reveal that the late Early-Paleozoic granitoids formed in the intraplate orogenic background originating from the subduction of the proto-Tethys Ocean and proto-Pacific Ocean around the margin of the east Gondwana supercontinent.

关键词： Late Early-Paleozoic Granites Intraplate orogeny Cathysian block Zircon U-Pb-Hf Isotopic composition

Nociceptors and Macrophages in Bacterial Meningitis:Partners in Crime?

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Neuroscience Bulletin 2024年第3期40卷 418-420页

作者： Fang gao Hongzhen Hu The Kimberly and Eric J.Waldman Department of Dermatology Icahn School of Medicine at Mount SinaiNew York NY10029USA The Nash Family Department of Neuroscience Icahn School of Medicine at Mount SinaiNew York NY10029USA The Mark Lebwohl Center for Neuroinfammation and Sensation Icahn School of Medicine at Mount SinaiNew York NY10029USA Friedman Brain Institute Icahn School of Medicine at Mount SinaiNew York NY10029USA

Bacterial meningitis is a serious and potentially life-threatening infection that affects the protective layers surrounding the brain and spinal cord,known as the meninges.Several types of bacteria,including Streptococcus pneumoniae,Neisseria meningitidis,and Haemophilus influenzae,can cause this condition.Certain populations,such as infants,children,immunocompromised adults,and the elderly,are particularly vulnerable to these pathogens.Symptoms of bacterial meningitis can manifest suddenly and may include high fever,severe and persistent headache,stiff neck,vomiting,sensitivity to light,and confusion or changes in mental state[1,2].Identifying these symptoms in infants can be more challenging and may lead to long-term disability or death[3].Despite the effectiveness of vaccines,it is crucial to understand how bacteria invade the brain and how our innate immune system responds to infection(Fig.1).

关键词： protective infection suddenly

On the core entropy of Newton maps

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Science China Mathematics 2024年第1期67卷 77-128页

作者： Yan gao Department of Mathematics Shenzhen UniversityShenzhen 518060China

In this paper,we define the core entropy for postcritically-finite Newton maps and study its continuity within this family.We show that the entropy function is not continuous in this family,which is different from the... 详细信息

关键词： core entropy extended Newton graph critical marking polynomial Newton map

Durable poly(binaphthyl-co-p-terphenyl piperidinium)-based anion exchange membranes with dual side chains

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Journal of Energy Chemistry 2024年第2期89卷 324-335,I0008页

作者： Weiting gao Xuelang gao Qiugen Zhang Aimei Zhu Qinglin Liu Department of Chemical&Biochemical Engineering Fujian Provincial Key Laboratory of Theoretical and Computational ChemistryThe College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Department of Chemistry Pohang University of Science and Technology(POSTECH)Pohang 790-784South Korea

Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.

关键词： Anion exchange membranes Backbone structure Fluorinated side chain Alkaline stability