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Spectral measurements of hypervelocity flow in an expansion tunnel

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Acta Mechanica Sinica 2019年第1期35卷 24-31,I0002页

作者： c.k.yuan k.Zhou Y.F.Liu Z.M.Hu Z.L.Jiang State key Laboratory of High-Temperature Gas Dynamic Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences. University of chinese Academy of Sciences Beijing 100049China china Academy of Aerospace Aerodynamics Beijing 100074China

Atmospheric reentry vehicles and planetary probes fly through the atmosphere at hypervelocity speed. At such speed, there is a significant proportion of heat load to the vehicle surface due to radiative heating. Accurate prediction needs a good knowledge of the radiation spectrum properties. In this paper, a high-speed camera and spectrograph coupled to an intensified charge-coupled device have bee n impleme nted to inv estigate the rad i at io n flow over a semi-cylinder model. The experiments were carried out in the JF16 expansi on timnel with secondary shock velocity of 7.9 km·s^-1. Results show that the emissio n spectrum comprises several atomic lines and molecular band systems. We give detailed data of the radiation spectrum, shock shape, shock detached distance and radiation intensity varying with space and wavelength. This valuable experimental dataset will be helpful to validate computational fluid dynamics codes and radiation models, which equates to increased prediction accuracy of radiation heating. Also, some suggestions for spectral measurement in hypervelocity flow field were list in the end.

关键词： Spectral measurement Hypervelocity flow Radiation Expansion tunnel

Net effect of air pollution controls on health risk in the Beijing-Tianjin-Hebei region during the 2022 winter Olympics and Paralympics

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Journal of Environmental Sciences 2024年第1期135卷 560-569页

作者： changqing Lin Peter k.k.Louie Alexis k.H.Lau Jimmy c.H.Fung Zibing yuan Minghui Tao Xuguo Zhang Md.Shakhaoat Hossain chengcai Li Xiang Qian Lao Division of Environment and Sustainability The Hong Kong University of Science and TechnologyHong KongChina Environmental Protection Department Hong Kong Government SARHong KongChina Department of civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina Guangdong-Hongkong-Macao Joint Laboratory of collaborative Innovation for Environmental Quality The Hong Kong University of Science and TechnologyHong KongChina Department of Mathematics The Hong Kong University of Science and TechnologyHong KongChina School of Environment and Energy South China University of TechnologyGuangzhou 510006China Hubei key Laboratory of critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China Department of Public Health and Informatics Jahangirnagar UniversityDhaka 1342Bangladesh Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China Jockey club School of Public Health and Primary care The Chinese University of Hong KongHong KongChina

Due to the non-linearity in ozone(O_(3))formation,reducing the emission of nitrogen oxides(NO_(x))may increase O_(3) *** the counteractive O_(3) response to NO_(x) reduction,overall impact of air pollution controls can be ambiguous when the assessments focus on the changes in pollutant *** this study,a risk-based method was used to gauge the net effect of air pollution controls on mortality risk in the Beijing–Tianjin–Hebei(BTH)region during the 2022 Winter Olympics and Paralympics(WOP).This mega-event presents a unique opportunity to investigate the efficacy of deep cuts in pollutant *** show that O_(3) concentrations greatly increased as nitrogen dioxide(NO_(2))concentrations decreased in the *** to the active photochemical formations,O_(3) became the dominant pollutant that affected human health during the *** the substantial O_(3) increases,the health benefits of NO_(2) reductions overwhelmed the adverse health effects of O_(3) increases in most regions of the BTH(at 81 out of 112 stations).After considering the impacts of particulate matter,the integrated health risk of air pollution mixtures declined almost everywhere in the *** results underscore the great necessity of changing the assessment paradigm of pollution control from using concentration-based methods to using risk-based *** with the carbon neutrality policy,stringent control of NO_(x)emission from combustion sources is a promising way to achieve synergistic control solutions for air pollution and climate change.

关键词： Ozone Nitrogen dioxide Health risk carbon neutrality Mega-events

Insights and implications of sexual dimorphism in osteoporosis

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Bone Research 2024年第1期12卷 20-49页

作者： yuan-yuan Zhang Na Xie Xiao-Dong Sun Edouard c.Nice Yih-cherng Liou canhua Huang Huili Zhu Zhisen Shen key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province Sichuan Research Center for Drug Precision Industrial TechnologyWest China School of PharmacySichuan UniversityChengdu 610041China West china School of Basic Medical Sciences&Forensic Medicine Sichuan UniversityChengdu 610041China Department of Biochemistry and Molecular Biology Monash UniversityClaytonVIC 3800Australia Department of Biological Sciences Faculty of ScienceNational University of SingaporeSingapore 117543Republic of Singapore Department of Biotherapy Cancer Center and State Key Laboratory of BiotherapyWest China Hospitaland West China School of Basic Medical Sciences&Forensic MedicineSichuan UniversityChengdu 610041China key Laboratory of Birth Defects and Related Diseases of Women and children of Ministry of Education Department of Reproductive MedicineWest China Second University Hospital of Sichuan UniversityChengduChina Department of Otorhinolaryngology and Head and Neck Surgery The Affiliated Lihuili HospitalNingbo University315040 NingboZhejiangChina

Osteoporosis,a metabolic bone disease characterized by low bone mineral density and deterioration of bone microarchitecture,has led to a high risk of fatal osteoporotic fractures *** evidence has revealed that sexual dimorphism is a notable feature of osteoporosis,with sex-specific differences in epidemiology and ***,females are more susceptible than males to osteoporosis,while males are more prone to disability or death from the *** date,sex chromosome abnormalities and steroid hormones have been proven to contribute greatly to sexual dimorphism in osteoporosis by regulating the functions of bone *** the sex-specific differences in osteoporosis and its related complications is essential for improving treatment strategies tailored to women and *** literature review focuses on the mechanisms underlying sexual dimorphism in osteoporosis,mainly in a population of aging patients,chronic glucocorticoid administration,and ***,we highlight the implications of sexual dimorphism for developing therapeutics and preventive strategies and screening approaches tailored to women and ***,the challenges in translating bench research to bedside treatments and future directions to overcome these obstacles will be discussed.

关键词： osteoporosis epidemiology overcome

competition of composition Fluctuation Modes in Weakly Segregated Salt-doped Symmetric Diblock copolymers

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chinese Journal of Polymer Science 2024年第9期42卷 1375-1385,I0008页

作者： yuan-Xin Zhou Xian kong South china Advanced Institute for Soft Matter Science and Technology School of Emergent Soft MatterSouth China University of TechnologyGuangzhou510640China Guangdong Provincial key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou510640China

Salt-doped block copolymers have widespread applications in batteries,fuel cells,semiconductors,and various industries,where their properties crucially depend on phase separation ***,investigations into salt-doped diblock copolymers have predominantly focused on microphase separation,overlooking the segregation between ionic and polymeric *** study employs weak segregation theory to explore the interplay between phase separation dominated by the polymer-modulated mode and the salt-out-modulated mode,corresponding to microscopic and macroscopic phase separations,*** comparing diblock copolymers doped with salts to those doped with neutral solvents,we elucidate the significant role of charged species in modulating phase *** phase separation mode exhibits a transition between the polymer-modulated and salt-out-modulated modes at different *** systems doped with neutral solvents,this transition is stepwise,while in salt-ion-doped systems,it is *** a sufficiently large Flory-Huggins parameter between ions and polymers,the salt-out-modulated mode becomes dominant,promoting macrophase *** to the solvation effect of salt ions,salt-doped systems are more inclined to undergo microphase ***,we explore factors influencing the critical wavenumber of phase separation,including doping level and the Flory-Huggins parameters between two blocks and between ions and polymeric *** findings reveal that in a neutral solvent environment,these factors alter only the boundary between micro-and macro-phase separations,leaving the critical wavenumber unchanged in microphase separation ***,in a salt-doped environment,the critical wavenumber of microphase separation varies with these *** provides valuable insights into the pivotal role of electrostatics in the phase separation of salt-doped block copolymers.

关键词： Block copolymer Phase separation Field theory Salt-doped

A modified stochastic model for LS+AR hybrid method and its application in polar motion short-term prediction

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Geodesy and Geodynamics 2024年第1期15卷 100-105页

作者： Fei Ye Yunbin yuan State key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China BeiDou High-precision Satellite Navigation and Location Service Hunan Engineering Research center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China Hunan continuously Operating Reference Stations(HNcORS)Data center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China

Short-term(up to 30 days)predictions of Earth Rotation Parameters(ERPs)such as Polar Motion(PM:PMX and PMY)play an essential role in real-time applications related to high-precision reference frame ***,least squares(LS)+auto-regressive(AR)hybrid method is one of the main techniques of PM ***,the weighted LS+AR hybrid method performs well for PM short-term ***,the corresponding covariance information of LS fitting residuals deserves further exploration in the AR *** this study,we have derived a modified stochastic model for the LS+AR hybrid method,namely the weighted LS+weighted AR hybrid *** using the PM data products of IERS EOP 14 c04,the numerical results indicate that for PM short-term forecasting,the proposed weighted LS+weighted AR hybrid method shows an advantage over both the LS+AR hybrid method and the weighted LS+AR hybrid *** to the mean absolute errors(MAEs)of PMX/PMY sho rt-term prediction of the LS+AR hybrid method and the weighted LS+AR hybrid method,the weighted LS+weighted AR hybrid method shows average improvements of 6.61%/12.08%and 0.24%/11.65%,***,for the slopes of the linear regression lines fitted to the errors of each method,the growth of the prediction error of the proposed method is slower than that of the other two methods.

关键词： Stochastic model LS+AR Short-term prediction The earth rotation parameter(ERP) Observation model

Improved LS+MAR hybrid method to UT1-UTc ultra-short-term prediction by using first-order-difference UT1-UTc

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Geodesy and Geodynamics 2024年第4期15卷 379-385页

作者： Fei Ye Yunbin yuan BeiDou High-precision Satellite Navigation and Location Service Hunan Engineering Research center Hunan Institute of Geomatics Sciences and TechnologyChangsha410007China State key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430077China HNcORS Data center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China

Accurate ultra-short-term prediction of the Earth rotation parameters(ERP)holds paramount impor-tance for real-time applications,particularly in reference frame *** them,diurnal rota-tion(UT1-UTc)which cannot be directly estimated through Global Navigation Satellite System(GNSS)techniques,significantly affects the rapid and ultra-rapid orbit determination of GNsS ***-ently,the traditional LS(least squares)+AR(autoregressive)and LS+MAR(multivariate autoregressive)hybrid methods stand as primary approaches for UT1-UTc ultra-short-term predictions(1-10 days).The LS+MAR hybrid method relies on the UT1-UTc and LOD(length of day)***,the correlation between LOD and first-order-difference UT1-UTc is stronger than that between LOD and *** light of this,and with the aid of the first-order-difference UT1-UTc,we propose an enhanced LS+MAR hybrid method to UT1-UTc ultra-short-term *** using the UT1-UTc and LOD data series of the IERS(International Earth Rotation and Reference Systems Service)EOP 14 c04 product,we conducted a thorough analysis and evaluation of the improved method's prediction performance compared to the traditional LS+AR and LS+MAR hybrid *** to the numerical results over more than 210 days,they demonstrate that,when considering the correlation information between the LoD and the first-order-difference UT1-UTc,the mean absolute errors(MAEs)of the improved LS+MAR hybrid method range from 21 to 934μs in 1-10 days *** comparison to the traditional LS+AR hybrid method,the MAEs show a reduction of 7-53μs in 1-10 days predictions,with corresponding improvement percentages ranging from 1 to 28%.Similarly,when compared to the traditional LS+MAR hybrid method,the MAEs have a reduction of 5-42μs in 1-10 days predictions,with corresponding improvement percentages ranging from 4-20%.Additionally,when aided by GNSS-derived LOD data series,the MAEs of improved LS+MAR hybrid method experience further

关键词： UT1-UTcultra-short-termprediction Rapidandultra-rapidproducts LS+AR and LS+MAR correlation First-order-differenceUT1-UTc

Tribological evaluation of thermoplastic polyurethane-based bearing materials under water lubrication:Effect of load,sliding speed,and temperature

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Friction 2024年第8期12卷 1801-1815页

作者： Shaoli JIANG Janet SSWONG Debashis PUHAN Tian yuan Xiuqin BAI chengqing yuan State key Laboratory of Maritime Technology and Safety Wuhan University of TechnologyWuhan 430063China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK Yusuf Hamied Department of chemistry University of CambridgeLensfield RoadCambridge CB21EWUK

Polymers are widely used in bearing *** the case of water-lubricated stern tube bearings,thermoplastic polyurethane(TPU)-based composites are used due to their excellent wear resistance,corrosion resistance,and tunable mechanical *** tribological performance,however,depends on operating *** this work,TPU was blended with carbon fiber,graphene platelet,and ultra-high molecular weight polyethylene(UHMWPE).Friction tests of TPU based-composites against copper countersurface were carried out in water to mimic the actual operating conditions of the *** of the resulting contacts were in the boundary lubrication regime,in which friction was attributed to both contact mechanics of asperities as well as water *** results show that the viscoelasticity of TPU has a considerable impact on its tribological *** lubrication at 50°c promotes the softening of polymer surface material during sliding,resulting in higher fluctuation in the coefficient of friction and wear *** is attributed to the reduced thermomechanical *** addition,Schallamach waviness is observed on worn *** tribological properties of TPU are significantly improved by the inclusion of carbon fiber,graphene platelet,and *** formation of graphene transfer-layers and UHMWPE transfer film reduces friction and wear loss,while the inclusion of carbon fiber enhances wear resistance due to improved mechanical properties and load bearing capacity.

关键词： friction thermoplastic polyurethane(TPU) water-lubricated bearings graphene platelet carbon fibers ultra-high molecular weight polyethylene(UHMWPE)

Trial application of the envelope method to the potential ambiguity problem

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Nuclear Science and Techniques 2024年第1期35卷 73-80页

作者： Li-yuan Hu Yu-Shou Song Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China college of Nuclear Science and Technology Harbin Engineering UniversityHarbin 150001China key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information TechnologyHarbin 150001China

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering *** a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering *** contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,***,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity *** this study,we conducted a trial application of the envelope method to the potential ambiguity *** envelope method was improved by including uncertainties in the experimental *** colliding systems of 16O+28Si at 215.2 MeV and 12c+12c at 1016 MeV were considered in the *** each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is *** calculated angular distributions were decomposed into nearside and farside scattering *** the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside *** capability of the envelope method to analyze the potential ambiguities was also discussed.

关键词： Elastic scattering Optical potential ambiguities Envelope method Nearside/farside decomposition

Discovery potential of the Glashow resonance in an air shower neutrino telescope

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chinese Physics c 2024年第8期48卷 266-275页

作者： Guo-yuan Huang School of Mathematics and Physics China University of GeosciencesWuhan 430074China Max-Planck-Institut für kernphysik Saupfercheckweg 169117 HeidelbergGermany

The in-ice or in-water cherenkov neutrino telescope,such as Icecube,has already proved its power in measuring the Glashow resonance by searching for the bump around E_(ν)=6.3PeV arising from the W-boson *** are many proposals for the next few decades for observations of cosmic tau neutrinos with extensive air showers,also known as tau neutrino *** air shower telescope is,in principle,sensitive to the Glashow resonance via the channel W→τν_(τ)followed by the tau decay in the air(e.g.,TAMBO,which has a geometric area of approximately 500km^(2)).Using a thorough numerical analysis,we find that the discovery significance can be up to 90%with a TAMBO-like setup if PeV neutrinos primarily originate from neutron decays,considering the flux parameters measured by Icecube as the *** presence of new physics affecting the neutrino flavor composition can also increase the ***,if ultrahigh-energy neutrinos are dominantly produced from meson decays,it will be statistically difficult for an advanced proposal such as TAMBO to discriminate the Glashow resonance induced byν¯e from the intrinsicντ/ν¯_(τ)*** have identified several limitations for such advanced telescopes,in comparison with the in-ice or in-water telescope,when measuring resonances:(i)a suppressed branching ratio of 11%for the decay W→τν_(τ);(ii)the smearing effect and reduced acceptance because the daughter neutrino takes away(y)∼75%of the energy from the W decay;and(iii)a large attenuation effect for Earth-skimming neutrinos with the resonance.

关键词： Ultrahigh-energy neutrinos Neutrino telescopes Glashow resonance