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Effect of Mo Addition on Microstructural Characteristics in a Re-containing Single Crystal Superalloy

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Journal of Materials Science & Technology 2015年第2期31卷 143-147页

作者： X.G.liu l.Wang l.h.lou J.Zhang Superalloys Division Institute of Metal ResearchChinese Academy of Sciences Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

The effect of Mo addition on microstructural characteristics of a nickel-base single crystal superalloy containing 4 wt% Re was investigated. The γ/γ’ partitioning ratios determined by energy dispersive spectrometer attached to a transmission electron microscope showed that the addition of Mo enhanced the partitioning of Re,W and Cr in the g matrix while decreased the concentration of Ta in the matrix. Synchrotron radiation diffraction was adopted to measure the γ/γ’ lattice misfit at room temperature. The results indicated that Mo addition changed the γ/γ’ lattice misfit towards larger negative as well as increased the tetragonal distortion of the γ lattice. Additionally,Mo addition led to microstructural instability and altered the precipitation behavior of topologically close-packed phases during 1100 C exposure. Instead of precipitating directly from the matrix,the μ phase was observed to be converted from the α phase which precipitated preferentially as a metastable intermediate in the alloy with high Mo content.

关键词： Superalloy Molybdenum Microstructure Partitioning

Effect of Solidification Condition and Carbon Content on the Morphology of MC Carbide in Directionally Solidified Nickel-base Superalloys

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Journal of Materials Science & Technology 2014年第12期30卷 1296-1300页

作者： X.W.li l.Wang J.S.Dong l.h.lou Superalloys Division Institute of Metal Research Chinese Academy of Sciences

Evolution of the morphology of MC carbides with the change of cooling rate and carbon content in two kinds of nickel-base superalloys, K417 G and DD33, has been investigated. The morphology of MC carbides evolves from faceted to script-like with increasing cooling rate. Varying the carbon content from 40X10-6 to 320X10-6, the morphology of carbides changes from blocky, rod-like into script-like. Scanning electron microscopy observation of deep-etched samples indicates that these carbides evolve from octahedral to dendritic and then into welldeveloped dendrites accordingly in a three-dimensional manner. The morphology evolution is discussed from the viewpoint of the preferential growth orientation of fcc crystals and the carbide growth rate during directional solidification.

关键词： Carbides morphology Directional solidification Three-dimensional microstructure Nickel-base superalloys

Effect of long-term Thermal Exposure on Microstructure and Stress Rupture Properties of Gh3535 Superalloy

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Journal of Materials Science & Technology 2015年第3期31卷 269-279页

作者： T.liu J.S.Dong l.Wang Z.J.li X.T.Zhou l.h.lou J.Zhang School of Materials Science and Engineering Dalian University of Technology Institute of Metal Research Chinese Academy of Sciences Shanghai Institute of Applied Physics Chinese Academy of Sciences Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

The evolution of microstructure and the stress rupture properties of long term thermally exposed Gh3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.

关键词： Gh3535 superalloy long term thermal exposure Micro

low-Cycle Fatigue Properties of Nickel-Based Superalloys Processed by high-Gradient Directional Solidification

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Acta Metallurgica Sinica(English letters) 2017年第9期30卷 878-886页

作者： Z.D.Fan D.Wang C.liu G.Zhang J.Shen l.h.lou J.Zhang Superalloys Division Institute of Metal ResearchChineseAcademy of SciencesShenyang 110016China Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Xi'an Thermal Power Research Institute Co. Ltd.Xi'an 710054China

The low-cycle fatigue （lCF） properties of DD10 （single-crystal） and DZ53 （columnar-grained） superalloys solidified by liquid-metal cooling （lMC） and high-rate solidification （hRS） processes have been systematically investi- gated. It was found that the lCF life of DZ53 solidified by lMC was obviously better than that solidified by hRS. In contrast, for DD10, lMC showed no remarkable influences on lCF properties at high temperature and only improved lCF properties at intermediate temperature. Microstructure examination showed that the cracks generally initiated at microp- ores in the subsurface at intermediate temperature. however, the cracks occurred on the surface due to oxidation, or persistent slip bands near script-MC at high temperature. Therefore, the benefits of lMC technique can be attributed to both of the reduced casting defects which significantly affect the lCF properties at intermediate temperature and the improved microstructural homogeneity which was strongly correlated to the lCF properties of alloys at high temperature.

关键词： Superalloys Rapid solidification low-cycle fatigue Microstructure

hydrochemical insights on the signatures and genesis of water resources in a high-altitude city on the Qinghai-Xizang Plateau, South-west China

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Frontiers of Environmental Science & Engineering 2024年第7期18卷 123-140页

作者： Jiutan liu Kexin lou Zongjun Gao Menghan Tan College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China

Water resources have crucial implications for the steady development of the urban social *** study investigated the hydrochemical signatures and genesis of water resources in the urban area of lhasa City(UAlC).To this end,several analyses,such as ion ratio analysis and correlation analysis,were performed by comprehensively applying mathematical statistics and integrated hydrochemical *** results show relatively low concentrations of major ions in the groundwater and surface water(GSW)of the *** primary anions and cations are hCO3-and Ca2+,reflecting the hCOg-Ca water ***,groundwater exhibits higher concentrations of key chemical components compared to surface *** are weakly alkaline,with ph values of 7.78 and 7.61,respectively,and they have low salinity with average concentrations of total dissolved solids being 190.74 and 112.17 mg/l,*** inputs have minimal influence on the hydrochemical features of GSw,whereas rock weathering is the dominant controlling ***,cation *** a significant *** influencing their hydrochemical *** to the isotope analysis(h and 180),the primary source of recharge for GSW is atmospheric precipitation,with some input from melted ice and ***,GSW samples from the UAlC show relatively similar 2h and 18O isotopic compositions,indicating the existence of a discernible hydraulic connection linking the two water *** research findings can serve as a valuable scientific reference and foundation for the sustainable development,effective utilization,and proper safeguarding of regional water resources in high-altitude areas.

关键词： Groundwater and surface water hydrochemical features Genesis mechanism Water quality Urban area of lhasa City

h∞ Robustness for Distributed Control in Autonomous Microgrids Considering Cyber Disturbances

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 696-706页

作者： Ge Cao Guannan lou Wei Gu lina Sheng School of Electrical Engineering Southeast UniversityNanjing 210096China

The physical connections and logical relationships between microgrids and communication networks allow microgrids to develop into typical cyber-physical systems(CPSs).With the extensive use of open communication mechanisms,the impact of cyber disturbances in public communication networks cannot be *** this paper,a parameter optimal method for a distributed secondary controller based on the robust control theory and consensus algorithm is presented to enhance the robustness of a secondary control system under data disturbance,parameter perturbation,and time ***,a distributed secondary control strategy of microgrids is demonstrated that coordinates frequency and voltage restoration and power ***,considering the impact of cyber events on the secondary control,a distributed robust controller gain design method is proposed to satisfy the h∞ performance *** solution of the distributed robust control is transformed into a linear matrix in equation problem and latency margin is simultaneously ***,a test microgrid CPS is simulated with and without time delay to investigate the impact of cyber events on system operational states and the effectiveness and robustness of the proposed method.

关键词： Cyber disturbance cyber-physical lsystem distributed control microgrid robust h∞control

A new 4-Ti-added polyoxometalate

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Tungsten 2024年第2期6卷 465-471页

作者： hai-lou li Chen lian Guo-Yu Yang MOE Key laboratory of Cluster Science School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 102488China

A new inorganic–organic hybrid 4-Ti-added polyoxometalate:[h_(2)N(Ch_(3))_(2)]_(2)Na_(3)h_(5)[{Ti(C_(2)O_(4))(h_(2)O)}_(2){Ti(C_(2)O_(4))}_(2)(B-β-SbW_(9)O_(33))_(2)]·22h_(2)O(1)has been successfully made and further characterized by infrared spectroscopy,thermogravimetric analysis,powder X-ray diff raction and single-crystal X-ray diff *** polyoxoanion of 1 exhibits a Krebs-type structure that is constructed from two[B-β-SbW_(9)O_(33)]^(9)−fragments fused together by a belt of four additional Ti atoms decorated by oxalate ***,1 as a heterogeneous catalyst exhibits high activity for Knoevenagel condensation under mild reaction conditions.

关键词： Polyoxometalate Ti-added POM Krebs-type structure Knoevenagel condensation

An Efficient Smoothing and Thresholding Image Segmentation Framework with Weighted Anisotropic-Isotropic Total Variation

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1369-1405页

作者： Kevin Bui Yifei lou Fredrick Park Jack Xin Department of Mathematics University of CaliforniaIrvineIrvineCA 92697-3875USA Department of Mathematics University of North CarolinaChapel HillChapel HillNC 27599.USA Department of Mathematics and Computer Science Whittier CollegeWhittierCA 90602USA

In this paper,we design an efficient,multi-stage image segmentation framework that incorporates a weighted difference of anisotropic and isotropic total variation(AITV).The segmentation framework generally consists of two stages:smoothing and thresholding,thus referred to as smoothing-and-thresholding(SaT).In the first stage,a smoothed image is obtained by an AITV-regularized Mumford-Shah(MS)model,which can be solved efficiently by the alternating direction method of multipliers(ADMMs)with a closed-form solution of a proximal operator of the l_(1)-αl_(2) *** convergence of the ADMM algorithm is *** the second stage,we threshold the smoothed image by K-means clustering to obtain the final segmentation *** experiments demonstrate that the proposed segmentation framework is versatile for both grayscale and color images,effcient in producing high-quality segmentation results within a few seconds,and robust to input images that are corrupted with noise,blur,or *** compare the AITV method with its original convex TV and nonconvex TVP(Ohowcasing the qualitative and quantitative advantages of our proposed method.

关键词： Image segmentation Non-convex optimization Mumford-Shah(MS)model Alternating direction method of multipliers(ADMMs) Proximal operator

Recent advances in photochemistry for positron emission tomography imaging

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Chinese Chemical letters 2024年第8期35卷 149-162页

作者： Jing-Jing Zhang lujun lou Rui lv Jiahui Chen Yinlong li Guangwei Wu lingchao Cai Steven h.liang Zhen Chen Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest BiomassJiangsu Key Lab of Biomass-Based Green Fuels and ChemicalsInternational Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China Department of Radiology and Imaging Sciences Emory UniversityAtlantaGA 30322United States

As a powerful noninvasive imaging technology,positron emission tomography(PET)has been playing an important role in disease theranostics and drug *** successful application of PET relies on not only the biological properties of PET tracers but also the availability of facile and efficient radiochemical reactions to enable practical production and widespread use of PET *** recently,photochemistry is emerging as a novel,mild and efficient approach to generating PET *** this review,we focus on the recent advances in newly developed photocatalytic radiochemical reactions,innovation on automated photochemical radiosynthesis modules,as well as implementation in late-stage radiolabeling and radio-pharmaceutical synthesis for PET *** believe that this review will inspire the development of more promising radiolabeling protocols for the preparation of clinically useful PET agents.

关键词： Positron emission tomography(PET) Fluorine-18 Carbon-11 Photocatalysis Automation late-stage functionalization