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Thermal decomposition mechanism and kinetics of bastnaesite in suspension roasting process:A comparative study in N_(2. and air atmospheres

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Journal of Rare Earths 2024年第9期42卷 1809-1816,I0006页

作者： wenbo Li Jijia chen Shaokai cheng {2. Sun Xiaolong Zhang school of Resources and Civil Engineering Northeastern UniversityShenyang110819China National-Local Joint Engineering Research Center of High-Efficient Exploitation Technology for Refractory Iron Ore Resources Shenyang110819China

To investigate the thermal decomposition behavior and reaction kinetics of bastnaesite in suspension roasting,the gas and solid products of bastnaesite roasted in N2.and air atmospheres were examined using a gas analyzer,X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).Subsequently,the kinetic parameters of bastnaesite in the suspension roasting process were derived and calculated using the isothermal *** results show that the decomposition product of bastnaesite in N_(2. is ***,once the roasting temperature exceeds 600℃,CO is generated in addition to CO_(2.,and all the XRD diffraction peaks of CeOF are shifted to the right,indicating that CO_(2. can oxidize CeOF and lead to the transformation of Ce(Ⅲ) into Ce(Ⅳ).When roasted in air,the decomposition product CeOF can be completely converted to CeF3 and Ce_(7)O_(12. as it easily ***,the reaction rate of bastnaesite in air is higher than that of N_(2.,and the starting reaction temperature is lower than that of N_(2..A large number of irregular cracks and holes appear on the surface of solid-phase products following suspension roasting,which are due to the thermal decomposition of bastnaesite that produces CO_(2. as well as the reconstruction of the lattice of the solid-phase *** reaction kinetic model of bastnaesite roasted in N_(2.(temperature range 600-750℃) and air(temperatu re range 500-575℃) confo rms to the A_(3/2. model with the mechanism function G(α)=-ln(1-α)^(2.3),and the reaction activation energy is 59.78 kj/mol and lnA is 1.65 s^(-1) in N_(2. *** air,the reaction activation energy is 100.30 kj/mol and lnA is 9.63 s^(-1).

关键词： Rare earths Bastnaesite Suspension roasting Thermal decomposition mechanism Reaction kinetics

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Research on the evaluation model of the modernization level of urban construction in Jiangsu Province,china

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Science china(Technological Sciences) 2010年第9期53卷 2510-2514页

作者： yang junyan1 & chen wen2.1 school of architecture,southeast university,Nanjing 2.0096,{2. 2.Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 2.0008,{2. 1. school of architecture Southeast University Nanjing 210096 China2. Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

The modernization of urban construction is a key index in the process of urbanization,and also is an important index to measure the level of socio-economic and cultural *** paper analyzes and explores the related concepts of modernization of urban construction,analyzes the situation and identity of urban construction layer by layer so as to establish an evaluation index system of the modernization level of urban construction and then the paper evaluates the modernization level of urban construction from four different angles,which are the perspectives of the urban planning control,the level of urban facilities,urban management,urban construction *** later analyzes the evaluation results by choosing Jiangsu Province as a research hierarchy from the scale chains of urban study and makes efforts to the operative and directive development direction.

关键词： modernization of urban construction index system evaluation model

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Realizing the excellent oxidation resistance of an environmental barrier coating through aluminum surface modification

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Journal of Advanced Ceramics 2024年第7期13卷 976-986页

作者： Lin Dong wen-Qi yang Lin {2. Guan-Jun yang Chang-Jiu Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Aerospace Engine Company Limited in china Aerospace Science and Technology Corporation Xi’an 710065China

The lifetime of Si-based environmental barrier coatings(EBCs)is constrained by thermally grown SiO_(2.oxidelayer(SiO_(2.-TGO),which can cause premature cracking and *** address this issue,a new approach for surfacemodification using aluminum is *** oxidation performance was examined in a 50 vol%H_(2.O-50 vol%O_(2.environment at 1350℃for up to 300 *** results indicate that a dense ytterbium aluminum garnet(YbAG)layer wasformed after modification,decreasing the porosity by 80%.Due to the elimination of fast diffusion channels and the lowoxygen permeability of YbAG,aluminum modification significantly reduced the growth rate of SiO_(2.-TGO by nearly twoorders of ***,its thickness decreased by more than 70%after 300 h of exposure.A diffusioncontrolled oxidation mechanism indicates that the modified dense surface is equivalent to an initial SiO_(2.layer with a specificthickness,causing a shift in the oxidation time and increasing the oxidation *** research provides valuableinsights for designing Si-based EBC with improved lifetimes.

关键词： environmental barrier coating(EBC) oxidation modification diffusion cracking

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Irreducible Representations of GL_(n)(C)of Minimal Gelfand-Kirillov Dimension

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Acta Mathematica Sinica,English Series 2024年第3期40卷 639-657页

作者： Zhan Qiang BAI yang yang {2. Dong wen LIU Bin Yong SUN school of Mathematical Sciences Soochow UniversitySuzhou 215006P.R.China school of Sciences JiangnanUniversityWui214122P.R.China school of Mathematical Sciences Zhejiang UniversityHangzhou 310058P.R.China Institute for Advanced Study in Mathematics Zhejiang UniversityHangzhou 310058P.R.China

In this article,by studying the Bernstein degrees and Goldie rank polynomials,we es-tablish a comparison between the irreducible representations of G=GL_(n)(C)possessing the minimal Gelfand-Kirillov dimension and those induced from finite-dimensional representations of the maximal parabolic subgroup of G of type(n-1,1).We give the transition matrix between the two bases for the corresponding coherent families.

关键词： Bernstein degree coherent continuation Gelfand-Kirillov dimension

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Sampling-efficient path planning and improved actor-critic-based obstacle avoidance for autonomous robots

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Science china(Information Sciences) 2024年第5期67卷 197-214页

作者： Yefeng yang Tao HUANG Tianqi WANG wenyu yang Han {2. Boyang LI Chih-yung wen Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic University Center for Control Theory and Guidance Technology Harbin Institute of Technology school of Engineering The University of Newcastle Research Center for Unmanned Autonomous Systems The Hong Kong Polytechnic University

Autonomous robots have garnered extensive utilization in diverse fields. Among the critical concerns for autonomous systems, path planning holds paramount importance. Notwithstanding considerable efforts in its development over the years, path planning for autonomous systems continues to grapple with challenges related to low planning efficiency and inadequate obstacle avoidance response in a timely *** study proposes a novel and systematic solution to the path planning problem within intricate office buildings. The solution consists of a global planner and a local planner. To handle the global planning aspect, an adaptive clustering-based dynamic programming rapidly exploring random tree(ACDP-RRT) algorithm is proposed. ACDP-RRT effectively identifies obstacles on the map by leveraging geometric *** obstacles are then represented as a collection of sequentially arranged convex polygons, optimizing the sampling region and significantly enhancing sampling efficiency. For local planning, a network decoupling actor-critic(ND-AC) algorithm is employed. The proposed ND-AC simplifies the local planner design process by integrating planning and control loops into a neural network(NN) trained via an end-to-end model-free deep reinforcement learning(DRL) framework. Moreover, the adoption of network decoupling(ND) techniques leads to an improved obstacle avoidance success rate when compared to conventional actor-critic(AC)-based methods. Extensive simulations and experiments are conducted to demonstrate the effectiveness and robustness of the proposed approach.

关键词： rapidly exploring random tree (RRT) adaptive clustering network decoupling actor critic (AC) path planning

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Durable dual-state duplex Si-HfO_(2.with excellent oxidation and cracking resistance

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Journal of Advanced Ceramics 2024年第3期13卷 388-401页

作者： Lin chen Jing-Chuan Luo wen-Qi {2. Chang-Jiu Li Guan-Jun {2. State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Aerospace Engine Company Limited in CASC Xi’an 710065China

The lifetime of Si bond coatings in environmental barrier coatings is constrained by phase-transition-induced cracking of the SiO_(2.*** this study,Si-HfO_(2.dual-state duplex composite materials are proposed to address this issue by partially forming HfSiO_(4)and minimizing the SiO_(2.*** as-prepared composite exhibited a structure comprising discrete HfO_(2.“bricks”embedded in a continuous Si“mortar”,while the oxidized state transformed into discrete HfSiO_(4)“bricks”within continuous thin SiO_(2.“mortars”.The results indicate that continuous thin SiO_(2.contributes to reducing the oxidation rate to a level comparable to that of pure Si,and discrete HfSiO_(4)particles aid in relieving phase transition-induced stress and inhibiting crack propagation,thereby enhancing oxidation and cracking resistance ***,the composite with 2. mol%HfO_(2.and a mean particle size of~500 nm at 1370℃exhibited a service lifetime 10 times greater than that of pure *** research provides valuable insights for designing Si-based bond coatings with improved service lifetime.

关键词： oxidation environmental barrier coatings(EBCs) phase transition cracking bond coatings

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Quantitative prediction model for the depth limit of oil accumulation in the deep carbonate rocks:A case study of Lower Ordovician in Tazhong area of Tarim Basin

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Petroleum Science 2024年第1期21卷 115-124页

作者： wen-yang Wang Xiong-Qi Pang Ya-Ping Wang Zhang-Xin {2. Fu-Jie Jiang Ying {2. State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Research Institute of Exploration and Development PetroChina Southwest Oil&Gas Field CompanyChengdu610041SichuanChina Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada

With continuous hydrocarbon exploration extending to deeper basins,the deepest industrial oil accumulation was discovered below 8,2.0 m,revealing a new exploration ***,the extent to which oil exploration can be extended,and the prediction of the depth limit of oil accumulation(DLOA),are issues that have attracted significant attention in petroleum *** it is difficult to characterize the evolution of the physical properties of the marine carbonate reservoir with burial depth,and the deepest drilling still cannot reach the ***,the DLOA cannot be predicted by directly establishing the relationship between the ratio of drilling to the dry layer and the *** this study,by establishing the relationships between the porosity and the depth and dry layer ratio of the carbonate reservoir,the relationships between the depth and dry layer ratio were obtained *** depth corresponding to a dry layer ratio of 100%is the *** on this,a quantitative prediction model for the DLOA was finally *** results indicate that the porosity of the carbonate reservoir,Lower Ordovician in Tazhong area of Tarim Basin,tends to decrease with burial depth,and manifests as an overall low porosity reservoir in deep *** critical porosity of the DLOA was 1.8%,which is the critical geological condition corresponding to a 100%dry layer ratio encountered in the *** depth of the DLOA was 9,000 *** study provides a new method for DLOA prediction that is beneficial for a deeper understanding of oil accumulation,and is of great importance for scientific guidance on deep oil drilling.

关键词： Deep layer Tarim Basin Hydrocarbon accumulation Depth limit of oil accumulation Prediction model

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Atomic layer deposition in advanced display technologies:from photoluminescence to encapsulation

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International Journal of Extreme Manufacturing 2024年第2期6卷 65-82页

作者： Rong chen Kun Cao Yanwei wen Fan {2. Jian Wang Xiao Liu Bin Shan State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China

Driven by the growing demand for next-generation displays,the development of advanced luminescent materials with exceptional photoelectric properties is rapidly accelerating,with such materials including quantum dots and phosphors,***,the primary challenge preventing the practical application of these luminescent materials lies in meeting the required durability *** layer deposition(ALD)has,therefore,been employed to stabilize luminescent materials,and as a result,flexible display devices have been fabricated through material modification,surface and interface engineering,encapsulation,cross-scale manufacturing,and *** addition,the appropriate equipment has been developed for both spatial ALD and fluidized ALD to satisfy the low-cost,high-efficiency,and high-reliability manufacturing *** strategic approach establishes the groundwork for the development of ultra-stable luminescent materials,highly efficient light-emitting diodes(LEDs),and thin-film ***,this significantly enhances their potential applicability in LED illumination and backlighted displays,marking a notable advancement in the display industry.

关键词： atomic layer deposition display luminescent encapsulation

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The centrosymmetric to non-centrosymmetric transformation induced by alkaline-earth cations producing infrared nonlinear optical AeMn_(6)Ga_(6)S_(16)(Ae=Ca,Sr)

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Science china Chemistry 2024年第9期67卷 2941-2948页

作者： yang-Ping Zhang Shao-Min Pei wen-Fa {2. Bin-wen Liu Xiao-Ming Jiang Guo-Cong Guo State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of china Fuzhou 350108China school of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China

Non-centrosymmetric(NCS)structure is an indispensable prerequisite for second-order nonlinear optical(NLO)***,the mainstream approach for designing new NCS structures still relies on chemical substitution,necessitating an urgent infusion of fresh *** this work,two isomorphic sulfides AeMn_(6)Ga_(6)S_(16)(Ae=Ca,1;Sr,2.are afforded by modifying the skeleton of centrosymmetric(CS)Mn_(2.Ga_(2.S_(5) via introducing strong electropositive alkaline-earth ***,the incorporation of Ca^(2.)/Sr^(2.)cations allows the elementary[MnGaS_(9)]_(∞)chains to reconfigure into bumpy[MnS_(6)]-[GaS_(4)]layers in a new engagement manner,thus enabling the conversion from CS to NCS *** modifications cause not only strong second-harmonic generation(SHG)responses(~1.5×benchmark AgGaS_(2.@1,700 nm),but also significantly feasible bandgaps(2.60-2.64 e V)compared to the sulfide Mn_(2.Ga_(2.S_(5)(1.36 e V),which ultimately facilitate ultrahigh laser-induced damage thresholds(4.4-6.6×AgGaS_(2.@1,064 nm for compounds 1 and 2..The present study offers an ingenious approach for the transformation of CS to NCS structure.

关键词： second-harmonic generation non-centrosymmetrical structure NLO functional motif solid-state method

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Visual test paper based on Au/δ-MnO_(2. hollow nanosphere oxidase-like activity regulation using hexavalent chromium as a smart switch

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Rare Metals 2024年第2期43卷 711-722页

作者： wen-Chang Zhuang Hai-Yue Zhang Zhen-yang {2. wen-Jing {2.g Wei-Dan Na Zhao Li Lin Tian school of Materials and Chemical Engineering Xuzhou University of TechnologyXuzhou221018China school of Chemistry and Environmental Science Yili Normal UniversityYining835000China

Paper-based sensing platform is a point of need analytical toolkit for safety ***,the sensitivity,specificity,and simplicity are still ***,we report a novel strategy(Au/δ-MnO_(2. hollow nanosphere and 3,3′,5,5′-tetramethylbenzidine(TMB)induced test strips for signal-on detection)that can be utilized for hexavalent chromium(Cr^(6+))***,Cr^(6+)(CrO_(4)^(2.)) as a smart switch can remarkably enhance the oxidase-like activity of Au/δ-MnO_(2. hollow *** presence of Cr^(6+) can regulate the surface electronic redistribution of Au/δ-MnO_(2. and adjust the geometric configuration,which leads to the improvement in oxidase-like activity of Au/δ-MnO_(2..As a proof-of-concept application,a visual paper-based sensing platform of Cr^(6+) along with quantitative analysis by the test strips was successfully *** paper-based sensing platform exhibits a linear range with excellent selectivity for other interfering substances and lower limit of detection of 0.09μmol·L^(−1),providing a promising toolkit at-home Cr^(6+) measurement and environmental monitoring.

关键词： Point of need Colorimetric biosensing platform Au/δ-MnO_(2. hollow nanosphere Test strip Cr^(6+)

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