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Evolution of mechanical properties,localized corrosion resistance and microstructure of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging

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Journal of Central South University 2024年第6期31卷 1790-1807页

作者： DAI Xuan-xuan li yu-zhang liU Sheng-dan YE ling-ying BAO Chong-jun School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of lightweight and High-strength Structural Materials Changsha 410083China Key Laboratory of Non-ferrous Metals Science and Engineering(Ministry of Education) Changsha 410083China Kunming Metallurgical Research Institute Co. Ltd.Kunming 650031China

The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron *** NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/*** results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'*** the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and *** NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.

关键词： Al-Zn-Mg-Cu alloy non-isothermal aging mechanical properties localized corrosion resistance microstructure

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EFFECT OF INSTABIliTIES OF FLOW ON MESOSCALE PREDICTABIliTY OF WEATHER SYSTEMS

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Journal of Hydrodynamics 2011年第2期23卷 193-203页

作者： LUO yu zhang li-feng Institute of Meteorology PLA University of Science and Technology Nanjing 211101

The numerical solution of Boussinesq equations is worked out as an initial-value problem to study the effect of the instabilities of flow on the initial error growth and mesoscale predictability. The development of weather systems depends on different dynamic instability mechanisms according to the spatial scales of the system and the development of mesoscale systems is determined by symmetric instability. Since symmetric instability dominates among the three types of dynamic instability, it makes the prediction of the associated mesoscale systems more sensitive to initial uncertainties. This indicates that the stronger instability leads to faster initial error growth and thus limits the mesoscale predictability. Besides dynamic instability, the impact of thermodynamic instability is also explored. The evolvement of convective instability manifests as dramatic variation in small spatial scale and short temporal scale, and furthermore, it exhibits the upscale growth. Since these features determine the initial error growth, the mesoscale systems arising from convective instability are less predictable and the upscale error growth limits the predictability of larger scales. The latent heating is responsible for changing the stability of flow and subsequently influencing the error growth and the predictability.

关键词： instabilities of flow mesoscale system predictability initial errors

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Electroless deposition of Ni on template of halloysite and its magnetic property

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 152-156页

作者： FU yu-bin zhang li-de ZHENG Ji-yong Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China Luoyang Ship Material Research Institute Luoyang 471039 China Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China Luoyang Ship Material Research Institute Luoyang 471039 China

Halloysite template, a ceramic substrate, is of a hollow cylindric structure, on which the fine Pd nanoparticles are uniformly formed by the reduction of palldate chloride to initiate electroless deposition. The electroless deposition of Ni is catalyzed by the Pd particles, which results in a uniform layer of Ni-P alloy on halloysite. The alloy is of a nanocrystalline structure, of which the average diameter is about 6 nm. After being heat-treated at 400 ℃, it contains both Ni and Ni12P5 crystal, meanwhile, the Ni crystal gets larger with an average size of 51.9 *** content of phosphorous in the Ni layer has a great influence on crystal structure. The metallized halloysite has a higher inherent coercive force, and a much lower saturation magnetization in its as-plated state, while after heattreatment, the inherent coercive force decreases drastically. These magnetic properties have great relationship with the superparamagnetism of Ni nanocrystalline and the stress anisotropy in Ni layer.

关键词： halloysite template electroless deposition Ni nanocrystalline inherent coercive force

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Growth of Aligned Carbon Nanotubes on Large Scale by Methane Decomposition with Deactivation Inhibitor

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Journal of Natural Gas Chemistry 2007年第4期16卷 382-388页

作者： Hao yu Zhili li Cheng zhang Feng Peng Hongjuan Wang School of Chemical and Energy Engineering South China University of Technology Guangzhou 510650 Guangdong China

The effects of additives containing iron or nickel during chemical vapor deposition （CVD） on the growth of carbon nanotubes （CNTs） by methane decomposition on Mo/MgO catalyst were investigated. Ferrocene and nickel nitrate were introduced as deactivation inhibitors by in-situ evaporation during CVD. The precisely controlled in-situ introduction of these inhibitors increased the surface renewal of catalyst, and therefore prevented the catalyst from deactivation. Using this method, aligned multi-walled CNTs with parallel mesopores can be produced on a large scale.

关键词： aligned carbon nanotubes chemical vapor deposition deactivation inhibitor methane decomposition Mo/MgO catalyst ferrocene nickel nitrate

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A novel TOA estimation method with effective NLOS error reduction

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 32-37页

作者： zhang Yi-heng CUI Qi-mei li yu-xiang zhang Ping Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Ministry of Education Wireless Technology Innovation Institute (WTI) Beijing 100876 China

It is well known that non-line-of-sight （NLOS） error has been the major factor impeding the enhancement of accuracy for time of arrival （TOA） estimation and wireless positioning. This article proposes a novel method of TOA estimation effectively reducing the NLOS error by 60%, comparing with the traditional timing and synchronization method. By constructing the orthogonal training sequences, this method converts the traditional TOA estimation to the detection of the first arrival path （FAP） in the NLOS multipath environment, and then estimates the TOA by the round-trip transmission （RTT） technology. Both theoretical analysis and numerical simulations prove that the method proposed in this article achieves better performance than the traditional methods.

关键词： TOA estimation NLOS error B3G

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Partial linear Model Averaging Prediction for Longitudinal Data

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Journal of Systems Science & Complexity 2024年第2期37卷 863-885页

作者： li Na FEI yu zhang Xinyu Faculty of Science Kunming University of Science and TechnologyKunming 650500China School of Statistics and Mathematics Yunnan University of Finance and EconomicsKunming 650221China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China

Prediction plays an important role in data *** averaging method generally provides better prediction than using any of its *** though model averaging has been extensively investigated under independent errors,few authors have considered model averaging for semiparametric models with correlated *** this paper,the authors offer an optimal model averaging method to improve the prediction in partially linear model for longitudinal *** model averaging weights are obtained by minimizing criterion,which is an unbiased estimator of the expected in-sample squared error loss plus a *** properties,including asymptotic optimality and consistency of averaging weights,are established under two scenarios:(i)All candidate models are misspecified;(ii)Correct models are available in the candidate *** studies and an empirical example show that the promise of the proposed procedure over other competitive methods.

关键词： Asymptotic optimality longitudinal data model averaging estimator partially linear model prediction

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U-Pb zircon geochronology of basaltic pyroclastic rocks from the basement beneath the Xisha Islands in the northwestern South China Sea and its geological significance

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Acta Oceanologica Sinica 2024年第2期43卷 83-93页

作者： yu zhang Kefu yu Shiying li Guangxi Laboratory on the Study of Coral Reefs in the South China Sea Guangxi UniversityNanning 530004China Coral Reef Research Center of China Guangxi UniversityNanning 530004China School of Marine Sciences Guangxi UniversityNanning 530004China Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of ScienceGuangzhou 510301China

As one of the micro-blocks dispersed in the South China Sea(SCS), the basement of the Xisha Islands has rarely been drilled because of the thick overlying Cenozoic sediments, which has led to a confused understanding of the pre-Cenozoic basement of the Xisha Islands. Well CK-1, a kilometer-scale major scientific drill in the Xisha Islands in the northwestern SCS, penetrated thick reefal limestone(0–888.4 m) and the underlying basement rocks(888.4–901.4 m). In this study, we present the zircon U-Pb ages of basement basaltic pyroclastic rocks from Well CK-1 in the Xisha Islands of the northwestern SCS to investigate the basement nature of the Xisha microblock. The basement of Well CK-1 consists of basaltic pyroclastic rocks on the seamount. The zircon grains yielded apparent ages ranging from ca. 2 138.9 Ma to ca. 36 Ma. The old group of zircon grains from Well CK-1 was considered to be inherited zircons. Two Cenozoic zircons gave a weighted mean 206Pb/238U age of(36.3 ± 1.1) Ma,Mean Squared Weighted Deviations(MSWD) = 1.2, which may represent the maximum age of the volcano eruption. The Yanshanian inherited zircons(116.9–105.7 Ma and 146.1–130.2 Ma) from Well CK-1 are consistent with the zircons from Well XK-1, indicating that the basement of Chenhang Island may be similar to that of Well XK-1. We propose that the Xisha micro-block may have developed on a uniform Late Jurassic metamorphic crystalline basement, intruded by Cretaceous granitic magma.

关键词： South China Sea Xisha Islands basaltic pyroclastic rocks zircon

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Coupled simulation of fluid-particle interaction for large complex granules:A resolved CFD-DEM method for modelling the airflow in a vertical fixed bed of irregular sinter particles

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Particuology 2024年第7期90卷 292-306页

作者： Chengzhi li yu zhang Jiahe Shen Wei zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China School of Transportation and Logistics Engineering Wuhan University of TechnologyWuhan 430063China Centre for Bulk Solids and Particulate Technologies The University of NewcastleCallaghan NSW 2308Australia

A resolved CFD-DEM method is proposed to simulate the fluid-particle interaction for large complex *** airflow in a vertical sinter fixed bed is numerically studied using this *** multi-sphere clumped method is used to create irregular sinter particles in *** immersed boundary method and dynamic cell refinement are applied to describe the fluid flow around particles with higher resolution,by which the fluid-particle interaction can be simulated more *** simulation results presented the packing voidage distributions and the airflow fields in the sinter beds of different single and mixed particle size *** bed pressure drops were simulated and the results were compared with the corresponding experimental *** good agreement indicated that the proposed resolved CFD-DEM method is an effective tool to model the fluid-particle interaction for irregular large granules in the gas-solid multi-phase systems.

关键词： Resolved CFD-DEM method Irregular sinter particles Multi-sphere clumped method Immersed boundary method Dynamic cell refinement

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Incorporation of perigastric tumor deposits into the TNM staging system for primary gastric cancer

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World Journal of Gastrointestinal Oncology 2023年第9期15卷 1605-1615页

作者： Yang li Shuo li Lu liu li-yu zhang Di Wu Tian-yu Xie Xin-Xin Wang Medical School of Chinese People's liberation Army The First Medical CenterChinese People's Liberation Army General HospitalBeijing 100853China Department of General Surgery The First Medical CenterChinese People's Liberation Army General HospitalBeijing 100853China

BACKGROUND The current prognostic significance of perigastric tumor deposits(TDs)in gastric cancer(GC)remains *** To assess the prognostic value of perigastric TDs and put forward a new TNM staging framework involving TDs for primary *** This study retrospectively analyzed the pathological data of 6672 patients with GC who underwent gastrectomy or surgery for GC with other diseases from January 1,2012 to December 31,2017 at the Chinese PLA General *** to the presence of perigastric TDs or not,the patients were divided into TD-positive and TD-negative groups by using the method of propensity score *** differences between TD-positive and TD-negative patients were analyzed using binary logistic regression *** Kaplan-Meier method was used to plot survival *** Cox regression modeling and the log-rank test were used to analyze the *** Perigastric TDs were found to be positive in 339(5.09%)of the 6672 patients with GC,among whom 237 were men(69.91%)and 102 were women(30.09%)(2.32:1).The median age was 59 years(range,27 to 78 years).Univariate and multivariate survival analyses indicated that TD-positive GC patients had a poorer prognosis than TD-negative patients(P<0.05).The 1-,3-,and 5-year overall survival rates of GC patients with TDs were 68.3%,19.6%,and 11.2%,respectively,and these were significantly poorer than those without TDs of the same *** was significant variation in survival according to TD locations among the GC patients(P<0.05).A new TNM staging framework for GC was formulated according to TD *** TDs appear in the gastric body,the original stages T1,T2,and T3 are classified as T4a with the new framework,and the original stages T4a and T4b both are classified as *** TDs appear in the lesser curvature,the previous stages N0,N1,N2,and N3 now both are classified as *** TDs appear in the greater curvature or the distant tissue,the patient should be categorized as

关键词： Tumor deposits Gastric cancer Prognosis Stage Overall survival

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Simulation of a torrential rainstorm in Xinjiang and gravity wave analysis

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Chinese Physics B 2018年第5期27卷 573-580页

作者： Rui Yang Yi liu ling-Kun Ran yu-li zhang Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

We used a weather research and forecasting model to simulate a torrential rainstorm that occurred in Xinjiang,China during June 16–17,*** model successfully simulated the rainfall area,precipitation intensity,and changes in *** identified a clear wave signal using the two-dimensional fast Fourier transform method;the waves propagated westwards,with wavelengths of 45–20 km,periods of 50–120 min,and phase velocities mainly concentrated in the-25 m/s to-10 m/s *** results of wavelet cross-spectral analysis further confirmed that the waves were gravity waves,peaking at 11:00 UTC,June 17,*** gravity wave signal was identified along 79.17–79.93°E,81.35–81.45°E and 81.5–81.83°*** gravity waves detected along 81.5–81.83°E corresponded well with precipitation that accumulated in 1 h,indicating that gravity waves could be considered a rainstorm precursor in future precipitation forecasts.

关键词： gravity wave rainstorm spectral analysis methods weather research and forecasting model

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