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Three-stage niobium mineralization at Bayan Obo, China

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National Science Review 2024年第4期11卷 102-110页

作者： Yan Yu yang Li Yu Liu Xiao-Xiao Ling Li-Guang Wu Li yang Lan yang Bo yang Yong-Gang Zhao Xian-Hua Li State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking University Mining Research Institute Baotou Iron and Steel(Group) Co.LTD State Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization

The Chinese Bayan Obo deposit is a world-class rare earth element(REE) deposit with considerable niobium(Nb) and iron(Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead(U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites—key Nb-bearing minerals—are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma(n = 99), 438 ± 7 Ma(n = 93), and 268 ± 5 Ma(n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

关键词： niobium mineralization U-Pb dating ferrocolumbite Bayan Obo

Time-Aware LSTM Neural Networks for Dynamic Personalized Recommendation on Business Intelligence

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Tsinghua Science and Technology 2024年第1期29卷 185-196页

作者： Xuan yang James A.Esquivel Graduate School Angeles University FoundationAngeles City 2009Philippines Shandong Provincial University Laboratory for Protected Horticulture Weifang University of Science and TechnologyWeifang 262700China

Personalized recommendation plays a critical role in providing decision-making support for product and service analysis in the field of business ***,deep neural network-based sequential recommendation models gained considerable ***,existing approaches pay litle attention to users'dynamically evolving interests,which are influenced by product attributes,especially product *** overcome these challenges,we propose a dynamic personalized recommendation model:***,we first embed product information and attribute information into a unified data ***,we exploit long short-term memory(LsTM)networks to characterize sequential behavior over multiple time periods and seize evolving interests by hierarchical LSTM ***,similarity values between users are measured through pairwise interest features,and personalized recommendation lists are generated.A series of experiments reveal the superiority of the proposed method compared withotheradvanced methods.

关键词： personalized recommendations evolving interests embedding LsTM networks

A stable staggered-grid finite-difference scheme for acoustic modeling beyond conventional stability limit

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Petroleum Science 2024年第1期21卷 182-194页

作者： Jing-Yi Xu yang Liu National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing 102249China China University of Petroleum(Beijing) Karamay CampusKaramay 834000XinjiangChina

Staggered-grid finite-difference(SGFD)schemes have been widely used in acoustic wave modeling for geophysical *** improved methods are proposed to enhance the accuracy of numerical ***,these methods are inevitably limited by the maximum Courant-Friedrichs-Lewy(CFL)numbers,making them unstable when modeling with large time sampling intervals or small grid *** solve this problem,we extend a stable SGFD scheme by controlling SGFD dispersion relations and maximizing the maximum CFL ***,to improve modeling stability,we minimize the error between the FD dispersion relation and the exact relation in the given wave-number region,and make the FD dispersion approach a given function outside the given wave-number area,thus breaking the conventional limits of the maximum CFL ***,to obtain high modeling accuracy,we use the SGFD scheme based on the Remez algorithm to compute the FD *** addition,the hybrid absorbing boundary condition is adopted to suppress boundary reflections and we find a suitable weighting coefficient for the proposed *** derivation and numerical modeling demonstrate that the proposed scheme can maintain high accuracy in the modeling process and the value of the maximum CFL number of the proposed scheme can exceed that of the conventional SGFD scheme when adopting a small maximum effective wavenumber,indicating that the proposed scheme improves stability during the modeling.

关键词： Acoustic wave Staggered-grid finite-difference(SGFD) modeling Courant-friedrichs-lewy(CFL)number Stability

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The δ15N values of foxtail millet （Setaria italica） and common millet （Panicum miliaceum） are reliable indicators of manuring practices

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Science China Earth Sciences 2024年第9期67卷 2910-2923页

作者： Jishuai yang Xiaoyan yang Ting YOU Fahu CHEN Key Scientific Research Base of Bioarchaeology in Cold and Arid Regions (National Cultural Heritage Administration) Key Laboratory of Western China's Environmental Systems (Ministry of Education)College of Earth and Environmental SciencesLanzhou University Group of Alpine Paleoecology and Human Adaptation (ALPHA) State Key Laboratory of Tibetan Plateau Earth SystemResources and Environment (TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of Sciences State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems College of Pastoral Agriculture Science and TechnologyLanzhou University

Millet agriculture, which originated in northern China, alongside rice agriculture, have nurtured the Chinese civilization. Prehistoric manuring practices likely promoted and maintained sustainable millet agricultural production in the loess area of northern China. However, ongoing controversy exists regarding the indicators of prehistoric manuring intensity of foxtail millet（Setaria italica） and common millet（Panicum miliaceum）. Here, we present the results of pot and field fertilization experiments on two millet types. Our findings suggest that manuring can significantly increase the δ15N values of foxtail millet,and its δ15N values increase with increasing manuring levels. The δ15N values of foxtail millet leaves are systematically greater than those of grains by approximately 1.6‰. Manuring could have a long-term residual impact on increasing the δ15N values of soil and millet crops. Combined with previous crop fertilization experiment results, we propose that the impact of manuring on the δ15N values of non-nitrogen-fixing crops is roughly consistent. The δ15N value and amount of manure are key factors determining the extent of change in plant δ15N values. The millet grain δ15N values can serve as reliable indicators of manuring practices. Finally, we provide an interpretive framework for assessing the correlation between manuring levels and the δ15N values of archaeological millet remains. The δ15N values of ancient millet grains suggest widespread and intensive manuring practices in prehistoric millet agriculture in northern China, spanning from the early yangshao period to the Longshan period.

关键词： Millet farming Manuring experiment Farming system Archaeobotany North China

Risk-Averse Two-Stage Distributionally Robust Economic Dispatch Model Under Uncertain Renewable Energy

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1514-1524页

作者： Ce yang Weiqing Sun Jiannan yang Dong Han Department of Control Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of Electrical Engineering University of Shanghai for Science and TechnologyShanghai 200093China School of Economics and Business Administration Chongqing UniversityChongqing 400044China

With the participation of large quantities of renewable energy in power system operations,their volatility and intermittence increases the difficulties and challenges of power system economic *** the uncertainty of renewable energy generation,based on the distributionally robust optimization method,a two-stage economic dispatch model is proposed to minimize the total operation *** this paper,it is assumed that the fluctuating of renewable power generation follows the unknown probability distribution that is restricted in an ambiguity set,which is established by utilizing the first-order moment information of available historical ***,the theory of conditional value-at-risk is introduced to transform the model into a tractable model,which we call robust counterpart *** on the stochastic dual dynamic programming method,an improved iterative algorithm is proposed to solve the robust counterpart ***,the convergence optimum can be obtained by the improved iterative algorithm,which performs a forward pass and backward pass repeatedly in each iterative ***,by comparing with other methods,the results on the modified IEEE 6-bus,118-bus,and 300-bus system show the effectiveness and advantages of the proposed model and method.

关键词： Energy and reserve co-dispatch distributionally robust conditional value-at-risk stochastic dual dynamic programming

Low-Frequency Stability Analysis of Power Electronic Traction Transformer Based Train-Network System

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1608-1617页

作者： Yi Hong yang Li Zhikang Shuai Hanyu yang College of Electrical and Information Engineering Hunan University and the Advanced Energy Technology Center of State Grid Shanghai Energy Interconnection Research Institute Co.Ltd.Shanghai 201203China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China College of Electrical Engineering and Controal Science in Nanjing Tech University Nanjing 211816China

Power electronic traction transformers(PETTs)will be increasingly applied to locomotives in the future for their small volume and light ***,similar to conventional trains,PETTs behave as constant power loads and may cause low-frequency oscillation(LFO)to the train-network *** solve this issue,a mathematical model of the PETT is firstly proposed and verified based on the extended describing function(EDF)method in this *** the proposed model,the LLC converter is simplified to an equivalent circuit consisting of a capacitor and a resistor in *** is further demonstrated that the model can apply to various LLC converters with different topologies and ***,when the parameter differences between cells are not obvious,the PETT can be simplified to a single-phase rectifier(i.e.,conventional train)by equivalent *** on the model of PETT,the system low-frequency stability and influential factors are analyzed by using the generalized Nyquist ***,the correctness and accuracy of theoretical analyses are validated by off-line and hardware-in-the-loop simulation results.

关键词： Extended describing function method impedance model low-frequency oscillation power electronic traction transformer train-network system

Pressure effects on metal/covalent-organic frameworks: structural and optical properties

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Science China Chemistry 2024年第9期67卷 2890-2903页

作者： Yixuan Wang Yunfeng yang Xinyi yang Bo Zou Synergetic Extreme Condition High-Pressure Science Center State Key Laboratory of Superhard Materials College of Physics Jilin University

Metal-organic frameworks(MOFs) and covalent organic frameworks(COFs) with highly ordered porous structure, tunable bandgap, large specific surface area and structural diversity, provide an appealing platform for the development of stimulus response, sensing, imaging and optoelectronics. Among various tuning methods, pressure engineering using the diamond anvil cell is a highly powerful in-situ technique, which can efficiently modulate the structural and optical properties of MOFs/*** is beyond the realization of traditional chemical methods. This review outlines the research progress in the experimentoriented discovery of new phases or unique properties under high pressure, including phase transition, abnormal compression,photoluminescence(PL) discoloration and enhancement. Notably, the improvement of PL quantum yield in MOFs could be achieved by pressure-treated engineering and hydrogen-bonding cooperativity effect. We also propose and establish the relationship between structure and optical properties under high pressure. Finally, the challenge and outlook of the current fields are summarized. We hope that this review will supply guidance for comprehending the development of high-pressure MOF/COF-related research fields, and offer novel strategies for designing more high-performance MOF/COF materials to ultimately expand their applications.

关键词： metal/covalent-organic frameworks pressure engineering phase transition abnormal compressive behaviors piezochromic behaviors emission enhancement

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Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

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Carbon Energy 2024年第4期6卷 164-221页

作者： Huilin Hou Gang Shao yang Wang Wai‐Yeung Wong Weiyou yang Institute of Micro/Nano Materials and Devices Ningbo University of TechnologyNingboChina School of Materials Science and Engineering Zhengzhou UniversityZhengzhouChina Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental *** a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC ***,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible ***,some prospects concerning the challenges and research directions in this area are proposed.

关键词： hydrogen photoanode photoelectrochemical substrates water splitting

免疫骨质疏松学:一个基于免疫学的骨质疏松新概念

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中华实验外科杂志 2022年第2期39卷 406-408页

作者：马聪杨越华郭源源刘平傅德皓上海交通大学附属第一人民医院骨科 200080 华中科技大学同济医学院附属梨园医院骨科武汉430077 华中科技大学同济医学院附属梨园医院药剂科武汉430077

"免疫骨质疏松学"探讨免疫系统在骨质疏松发病机制中的作用, 以及免疫系统与骨骼系统之间的相互调控。自2018年提出以来, 备受骨代谢研究领域关注, 大量临床与基础研究围绕此概念展开, 本文就近年研究进展作一综述。

关键词：免疫骨质疏松学免疫细胞

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