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Growth characteristics and response to climate change of Larix Miller tree-ring in china

Science china Earth Sciences 2010年第6期53卷 871-879页

作者： SUN Yu1,4, WANG LiLi1,2.3, CHEN Jin5, DUAN JianPing1,4, SHAO XueMei1,2.& CHEN KeLong6 1 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101,{2. 2.Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085,{2. 3 Institute of Desert and Meteorology,{2. Meteorological Administration, Urumqi 830002.{2. 4 Graduate university of Chinese Academy of Sciences, Beijing 100049,{2. 5 Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044,{2. 6 school of Life and Geography Sciences, Qinghai Normal university, Xining 810008,{2. Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Graduate university of Chinese Academy of Sciences Beijing China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Institute of Desert and Meteorology China Meteorological Administration Urumqi China Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China school of Life and Geography Sciences Qinghai Normal University Xining China

As one of the earliest species used in dendrochronological studies, Larix responds sensitively to climate change. In this study, nine larch species and one variety from eleven sites were collected to study the growth characteristics of tree-ring width using dendrochronological methods. Ten residual tree-ring chronologies were developed to analyze their relationships with regional standardized anomaly series by Pearson’s correlation analysis. The results suggest that most of the chronologies had significantly positive correlations with the mean temperature and mean maximum temperature in May. The spring temperature evidently limited the radial growth of the larch species without precipitation control. The largest mean tree-ring width was found in Himalayan Larch in Jilong, whereas Master Larch in Si’er reflected the smallest mean value. Both species presented little climate information in this study. Chinese, Potanin, and Tibetan larches are significantly correlated with climate change, implying a huge potential for climate history reconstruction. The elevation of the sampling sites appears to be an important condition for tree-ring growth of larches responding to climate factors.

关键词： Larix Miller tree-ring climate change mean temperature in May

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Initial precursor reaction mechanism of CVD-HfC coating based on density functional theory

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Chinese Journal of Aeronautics 2024年第7期37卷 511-521页

作者： Yunzhou LIN Yulei zhang Yanqin FU Jian zhang Jing’an KONG Ruicong CHEN State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China Henan Key Laboratory of High Performance Carbon Fiber Reinforced Composites Carbon Matrix Composites Research InstituteHenan Academy of SciencesZhengzhou 450046China

Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-CH_(4)-H_(2.-Ar system via Chemical Vapor Deposition(CVD),which has been found widely applied to C/C ***,an analysis of the reactions that occur in the initial stage of the CVD-HfC coating process is presented using Density Functional Theory(DFT)and Transition State Theory(TST)at the B3LYP/Lanl2.Z *** results reveal that HfCl4 can only cleave to produce hypochlorite,which will further react with methyl to synthesize intermediates to form *** to the analysis of the energy barrier and reaction constant,HfCl preferentially reacts with methyl groups to form complex adsorptive intermediates at 1573 *** a C—Hf bond production energy of 2.2.8 kcal/mol(1 kcal=4.18 kJ),the reaction rate constant of HfCl+CH is calculated to be 2.15×10^(-18) cm^(3)/s at 1573 ***,both the simulation and experimental results exhibit that the upward trend of reaction rate constants with temperature is also consistent with the deposition rate,indicating that the growth curve of the reaction rate constants tends to flatten *** proposed reaction model of the precursor’s decomposition and reconstruction during deposition process has significant implication for the process guidance.

关键词： Carbon composite HfC coating Chemical vapor deposition Density functional theory Precursor reaction mechanism

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Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation

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Journal of Environmental Sciences 2024年第4期138卷 709-718页

作者： Shuo Hu Jianghao zhang Xueyan Chen Xiaoxiao Qin Jinshui Yao Changbin zhang school of Materials Science&Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China university of Chinese Academy of Sciences Beijing 100049China

Formaldehyde(HCHO)is a common indoor pollutant that is detrimental to human *** efficient removal has become an urgent demand to reduce the public health *** this work,Ag-MnO_(x)-based catalysts were prepared and activated under different atmosphere(i.e.,air,hydrogen(H_(2.)and carbon monoxide(CO))for efficient oxidation of *** catalyst activated with CO(Ag/Mn-CO)displayed the highest activity among the tested samples with 90% conversion at 100℃ under a gas space velocity of 75,000 mL/(g_(cat)·hr).Complementary characterizations demonstrate that CO reduction treatment resulted in synergically regulated content of surface oxygen on support to adsorb/activate HCHO and size of Ag particle to dissociate oxygen to oxidize the adsorbed *** contrast,other catalysts lack for either abundant surface oxygen species or metallic silver with the appropriate particle size,so that the integrate activity is limited by one specific reaction *** study contributes to elucidating the mechanisms regulating the oxidation activity of Ag-based catalysts.

关键词： HCHO oxidation Ag-MnO_(x)-based catalyst Activation condition Synergic regulation Surface oxygen Oxidized Ag

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Reconstruction of particle distribution for tomographic particle image velocimetry based on unsupervised learning method

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Particuology 2024年第10期93卷 349-363页

作者： Duanyu zhang Haoqin Huang Wu Zhou Mingjun Feng Dapeng zhang Limin Gao school of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an710072China

The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.

关键词： Tomographic particle image velocimetry 3D reconstruction Unsupervised learning Convolutional neural network

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Effect of temperature and time on the precipitation ofκ-carbides in Fe-2.Mn-10Al-0.8C low-density steels:Aging mechanism and its impact on material properties

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2189-2198页

作者： Yulin Gao Min zhang Rui Wang Xinxin zhang Zhunli Tan Xiaoyu Chong school of Mechanical Electronic and Control EngineeringMaterials Science and Engineering Research CenterBeijing Jiaotong UniversityBeijing 100044China Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

In low-density steel,κ-carbides primarily precipitate in the form of nanoscale particles within austenite ***,their precipitation within ferrite matrix grains has not been comprehensively explored,and the second-phase evolution mechanism during aging remains *** this study,the crystallographic characteristics and morphological evolution ofκ-carbides in Fe-2.Mn-10Al-0.8C(wt%)low-density steel at different aging temperatures and times and the impacts of these changes on the steels’microhardness and properties were comprehensively *** different heat treatment conditions,intragranularκ-carbides exhibited various morpho-logical and crystallographic characteristics,such as acicular,spherical,and short rod-like *** the initial stage of aging,acicularκ-carbides primarily precipitated,accompanied by a few spherical carbides.κ-Carbides grew and coarsened with aging time,the spherical carbides were considerably reduced,and rod-like carbides *** hardness testing demonstrated that the material’s hardness was affected by the volume fraction,morphology,and size ofκ-*** aging at higher temperatures led to an increase in carbide size and volume fraction,resulting in a gradual rise in *** deformation,the primary mechanisms for strengthening were dislocation strengthening and second-phase *** on these findings,potential strategies for improving material strength are proposed.

关键词： low-density steel κ-carbide solution-aging treatment hardness

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Cooperative effect of sodium lauryl sulfate collector and sodium pyrophosphate depressant on the flotation separation of lead oxide minerals from hematite

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 1975-1984页

作者： Honghu Tang Bingjian Liu Mengshan Li Qiancheng zhang Xiongxing zhang Feng Jiang school of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Engineering Research Center of Ministry of Education for Carbon Emission Reduction in Metal Resource Exploitation and Utilization Central South UniversityChangsha 410083China

As a cornerstone of the national economy,the iron and steel industry generates a significant amount of sintering dust containing both valuable lead resources and deleterious *** is a promising technique for lead recovery from sintering dust,but efficient separation from Fe_(2.O_(3) is still *** study investigated the cooperative effect of sodium lauryl sulfate(SLS,C_(12.H_(2.)SO_(4)Na)and sodium pyrophosphate(SPP,Na_(4)P_(2.O_(7))on the selective flotation of lead oxide minerals(PbOHCl and PbSO_(4))from hematite(Fe_(2.O_(3)).Optimal flotation conditions were first identified,resulting in high recovery of lead oxide minerals while inhibiting Fe_(2.O_(3) *** potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis,adsorption capacity analysis,and X-ray photoelectron spectroscopy(XPS)studies offer insights into the adsorption behaviors of the reagents on mineral surfaces,revealing strong adsorption of SLS on PbOHCl and PbSO_(4) surfaces and remarkable adsorption of SPP on Fe_(2.O_(3).The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior,highlighting the pivotal role of reagent adsorption in the separation *** findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery,paving the way for sustainable resource management in the iron and steel industry.

关键词： sintering dust flotation separation sodium lauryl sulfate sodium pyrophosphate selective adsorption

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High strength mullite-bond SiC porous ceramics fabricated by digital light processing

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Journal of Advanced Ceramics 2024年第1期13卷 53-62页

作者： Jian Sun Jingde zhang Xu zhang Zihe Li Jianzhang Li Sijie Wei Weibin zhang Weili Wang Guifang Han Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) School of Materials Science and EngineeringShandong UniversityJinan 250061China Key Laboratory of Special Functional Aggregated Materials Ministry of EducationShandong UniversityJinan 250100China Materials and Structures Research Centre Department of Mechanical EngineeringUniversity of BathBath BA27AYUK National Engineering Research Centre of Ceramic Matrix Composite Manufacture Technology Xi’an Golden Mountain Ceramic Composites Co.Ltd.Xi’an 710118China school of Physics and Materials Science Changji UniversityChangji 831100China

Fabricating SiC ceramics via the digital light processing(DLP)technology is of great challenge due to strong light absorption and high refractive index of deep-colored SiC powders,which highly differ from those of resin,and thus significantly affect the curing performance of the photosensitive SiC *** this paper,a thin silicon oxide(SiO_(2.)layer was in-situ formed on the surface of SiC powders by pre-oxidation *** method was proven to effectively improve the curing ability of SiC *** SiC photosensitive slurry was fabricated with solid content of 55 vol%and viscosity of 7.77 Pa·s(shear rate of 30 s^(−1)).The curing thickness was 50μm with exposure time of only 5 ***,a well-designed sintering additive was added to completely convert low-strength SiO_(2. into mullite reinforcement during *** mullite-bond SiC ceramics were successfully *** flexural strength of SiC ceramics sintered at 1550℃in air reached 97.6 MPa with porosity of 39.2.vol%,as high as those prepared by spark plasma sintering(SPS)techniques.

关键词： digital light processing(DLP) SiC ceramics pre-oxidation mullite-bond SiC mechanical properties

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Application of the computer-aided Quenching Technology on the Connecting Bar of 42.rMo4

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Journal of Shanghai Jiaotong university(Science) 2010年第5期15卷 596-599页

作者：左训伟周澍陈乃录廖波 Shanghai Key Laboratory of Materials Laser Processing and Modifiction Shanghai Jiaotong University school of Materials Science and Engineering Yanshan University

In order to obtain the desired mechanical properties of connecting bar after quenching and tempering,and reduce the cracking tendency and distortion,a program of controllable quenching was ***,a computer-aided quenchi... 详细信息

关键词： heat treatment quenching and tempering controllable quenching connecting bar

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Synergistic enhancement of Ce-ZnO/g-C_(3)N_(4)photocatalytic performance using N,O-bis-vacancy induction and S-scheme heterojunctions

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Journal of Rare Earths 2024年第5期42卷 817-826,I0001页

作者： Guyu zhang Yuan zhang Xinlei Zhao Yujiang Jiao Yumin Yan Jianhui Jiang Engineering Laboratory of Chemical Resources Utilization in South Xinjiang of Xinjiang Production and Construction Corps College of Chemistry a Chemical EngineeringTarimUniversityAlar843300China

The photocatalytic decontamination of organic pollutants is an environmentally friendly and efficient water treatment *** introduction of vacancies,heterojunctions,and doping can enhance the performance of photocatalysts for such *** this study,N,O double-vacancy Ce-ZnO/g-C_(3)N_(4)S-scheme heterojunction photocatalysts were prepared,It is found that the electron separation and transfer efficiencies are considerably improved by the presence of nitrogen vacancies in graphitic ca rbon nitride(g-C_(3)N_(4))and oxygen vacancies in ZnO,in addition to the S-scheme heterojunction created between the two *** the degradation of methylene blue and ciprofloxacin,the degradation rates exhibited by Ce-ZnO/g-C_(3)N_(4)are significantly higher than those of the g=C_(3)N_(4)/ZnO *** remarkable photocatalytic performance of Ce-ZnO/g-C_(3)N_(4)may result from three key factors;(ⅰ)Ce doping,which produces impurity energy levels;(ⅱ)the generation of electron capture centres by the N and O vacancies;and(ⅲ)the synergistic effect of the S-type heterojunction formed at the interface between the two materials,This study therefore provides new approaches for the use of doping,vacancies,and heterojunctions to induce the efficient degradation of organic pollutants.

关键词： Photocatalysis Vacancy S-scheme Ce-ZnO/g-C_(3)N_(4) Degradation Rare earths

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Principle of Interaction between Plastic Volumetric and Shear Strains and the Constitutive Model for Geotechnical Materials

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工程科学（英文版） 2007年第2期5卷 129-138页

作者： Wang Jingtao(1.Department of Architectural Engineering, Xinyang Normal university, Xinyang 464000, Henan, china {2.{{2. of Civil Engineering and Mechanics, Huazhong university of Science and Technology, wuhan 430074, china)

Here is proposed the principle of interaction between plastic volumetric and shear strains, revealing the main origin of generating the complexity and variety of deformations for geotechnical materials. Here are also explained the manners of the interaction between plastic volumetric and shear strains and the conditions of generating shear dilatancy. It is demonstrated that dependency of the stress path exists and is a combination of effects of this interaction. According to this principle, it is theoretically proved that the space critical state line exists, and is unique and independent of the stress history. Based on this principle, the constitutive models that are able completely and accurately to characterize the basic behavior features for geotechnical materials have been constructed within the framework of thermodynamics. What is determined is a general expression of the constitutive relation as well as the inequality of the dissipative potential increment for obeying the second law of thermodynamics.

关键词： interaction between volumetric and shear strains constitutive model for rock and soil dependency of stress path pressure-sensitivity shear dilatancy

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