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Contrasts of bimodal tropical instability waves(TIWs)-induced wind stress perturbations in the Pacific Ocean among observations,ocean models,and coupled climate models

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Journal of Oceanology and Limnology 2024年第1期42卷 1-23页

作者： kai Ma Chuanyu LIU Junli XU Fan WANG School of mathematics and Physics Research Institute for Mathematics and Interdisciplinary SciencesQingdao University of Science and TechnologyQingdao 266100China Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China Pilot National Laboratory for marine Science and Technology(Qingdao) Qingdao 266237China

The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean.However,an overlooked fact by previous studies is that the loosely defined“TIWs”actually consist of two modes,including the Yanai wave-based TIW on the equator(hereafter eTIW)and the Rossby wave-based TIW off the equator(hereafter vTIW).Hence,the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored.In this study,individual coupling relationships are established for both eTIW and v TIW,including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations,and the relationship between the TIW-induced wind stress perturbation divergence(curl)and the downwind(crosswind)TIW-induced SST gradients.Results show that,due to different distributions of eTIW and vTIW,the coupling strength induced by the eTIW is stronger on the equator,and that by the vTIW is stronger off the equator.The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs.We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models.However,the coupling relationships cannot be well represented in most numerical models.Finally,we confirmed that higher resolution usually corresponds to more accurate simulation.Therefore,the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.

关键词： bimodal tropical instability waves mesoscale air-sea interaction coupled models Yanai wave

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Kernel based statistic: identifying topological differences in brain networks

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Intelligent Medicine 2022年第1期2卷 30-40页

作者： kai Ma Wei Shao Qi Zhu Daoqiang Zhang College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsMIIT Key Laboratory of Pattern Analysis and Machine IntelligenceNanjingJiangsu 210016China

Background Brain network describing interconnections between brain regions contains abundant topological information.It is a challenge for the existing statistical methods(e.g.,t test)to investigate the topological differences of brain networks.Methods We proposed a kernel based statistic framework for identifying topological differences in brain networks.In our framework,the topological similarities between paired brain networks were measured by graph kernels.Then,graph kernels are embedded into maximum mean discrepancy for calculating kernel based test statistic.Based on this test statistic,we adopted conditional Monte Carlo simulation to compute the statistical significance(i.e.,P value)and statistical power.We recruited 33 patients with Alzheimer’s disease(AD),33 patients with early mild cognitive impairment(EMCI),33 patients with late mild cognitive impairment(LMCI)and 33 normal controls(NC)in our experiment.There are no statistical differences in demographic information between patients and NC.The compared state-of-the-art statistical methods include t test,t squared test,two-sample permutation test and non-normal test.Results We applied the proposed shortest path matched kernel to our framework for investigating the statistical differences of shortest path topological structures in brain networks of AD and NC.We compared our method with the existing state-of-the-art statistical methods in brain network characteristic including clustering coefficient and functional connection among EMCI,LMCI,AD,and NC.The results indicate that our framework can capture the statistically discriminative shortest path topological structures,such as shortest path from right rolandic operculum to right supplementary motor area(P=0.00314,statistical power=0.803).In clustering coefficient and functional connection,our framework outperforms the state-of-the-art statistical methods,such as P=0.0013 and statistical power=0.83 in the analysis of AD and NC.Conclusion Our proposed kernel based statistic framework not only can be used to

关键词： Brain network Conditional monte carlo Graph kernel Statistical analysis Topological difference

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Comparative Study on Corrosion Behavior and Mechanism of As-Cast Mg-Zn-Y and Mg-Zn-Gd Alloys

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Acta Metallurgica Sinica(English Letters) 2023年第2期36卷 310-322页

作者： Guoqiang Xi Xuhan Zhao Yanlong ma Yu Mou Ju Xiong kai Ma Jingfeng Wang College of material Science and Engineering Chongqing University of TechnologyChongqing400054China College of materials Science and Engineering Chongqing UniversityChongqing400044China

Rare earth(RE)elements have large solid solubility in magnesium and are widely used to regulate the microstructure and property of advanced magnesium alloys.However,different kinds of RE elements have different effects on microstructure and property of the alloy.In this study,a Mg-Zn-Y alloy and a Mg-Zn-Gd alloy with alloying elements of the same atomic percentage were designed to clarify the effect of yttrium(Y)and gadolinium(Gd)on the corrosion behavior of as-cast MgZn_(2)_Y(2.66) and MgZn_(2)Gd_(2.66)alloys.The results show that the MgZn_(2)_Y(2.66) alloy is mainly composed ofα-Mg phase and long period stacking ordered(LPSO)phase,while MgZn_(2)Gd_(2.66)alloy is mainly composed ofα-Mg phase and(Mg,Gd)_(3)Zn phase(W phase).Generally speaking,the corrosion phenomena of the two alloys in 3.5 wt%NaCl solution are similar.In the early stages of exposure,the alloys underwent uniform corrosion at a relatively low corrosion rate.With prolonged exposure,localized corrosion became dominated and the corrosion rate was greatly increased.However,the corrosion rate of the MgZn_(2)_Y(2.66) alloy,in terms of the corrosion current density,is about one order of magnitude lower than that of the MgZn_(2)Gd_(2.66)alloy.The high corrosion resistance of the MgZn_(2)_Y(2.66) alloy is mainly attributed to the presence of LPSO phase in form of continuous networks and the relatively high corrosion resistance of the corrosion product layer on the alloy.

关键词： magnesium alloys Rare earth Long period stacking ordered(LPSO)phase Microstructure Corrosion

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Improving Ductility and Anisotropy by Dynamic Recrystallization in Ti/Mg Laminated Metal Composite

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 1946-1958页

作者： Taiqian Mo Huaqiang Xiao Bo Lin Wei Li kai Ma School of Mechanical Engineering Guizhou UniversityGuiyang 550025China College of materials Science and Engineering Chongqing UniversityChongqing 400044China Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Ti/Mg laminated metal composites(LMCs)were processed by hot roll bonding and subsequent annealing at 200℃and300℃for 1 h,and the effect of dynamic recrystallization on the microstructure and anisotropy behavior was investigated in detail.The results revealed that,in both as-rolled and annealed Ti/Mg LMCs,the inhomogeneous distribution in the microstructure of Mg layers near the interface and near the center was related to the effect of friction between the roller and sheet surface and uncoordinated deformation between constituent layers.With increasing annealing temperature,Ti/Mg LMCs exhibited excellent elongation without sacrificing strength properties,which was mainly due to the improvement in bonding strength and the increasing strain gradient at the interface between soft and hard layers after annealing treatment.Besides,the increasing Schmid factors(SFs)of prismatic slip and pyramidal slip in Mg layers contributed to the improved plastic deformation ability of Ti/Mg LMCs.The experimental analysis indicated that the presence of Mg alloys resulted in the microstructure and mechanical properties of LMCs were different along various loading directions,and annealing treatment can effectively inhibit the anisotropic behavior of Ti/Mg LMCs resulting from the weakening of basal texture in the Mg layer.

关键词： Ti/Mg laminated metal composites Dynamic recrystallization Microstructure Mechanical propertiesAnisotropy

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Time-dependent Aharonov–Casher effect on noncommutative space

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Communications in Theoretical Physics 2023年第1期75卷 96-101页

作者： Tao Wang kai Ma Department of Physics Shaanxi University of TechnologyHanzhong 723000ShaanxiChina

In this paper,we study the time-dependent Aharonov-Casher effect and its corrections due to spatial noncommutativity.Given that the charge of the infinite line in the Aharonov-Casher effect can adiabatically vary with time,we show that the original Aharonov-Casher phase receives an adiabatic correction,which is characterized by the time-dependent charge density.Based on Seiberg-Witten map,we show that noncommutative corrections to the time-dependent Aharonov-Casher phase contains not only an adiabatic term but also a constant contribution depending on the frequency of the varying electric field.

关键词： noncommutative space Aharonov–Casher effect minimal length

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A Practical Approach to Constructing a Geological Knowledge Graph:A Case Study of Mineral Exploration Data

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地球科学学刊:英文版 2023年第5期34卷 1374-1389页

作者： Qinjun Qiu Bin Wang kai Ma Hairong Lü Liufeng Tao Zhong Xie Collaborative Innovation Center of Geo-Information Technology for Smart Central Plains Zhengzhou 450046China Key Laboratory of Spatiotemporal Perception and Intelligent Processing Ministry of Natural ResourcesZhengzhou 450046China Key Laboratory of Geological Survey and Evaluation of Ministry of Education China University of GeosciencesWuhan 430074China Hubei Key Laboratory of Intelligent Vision Based Monitoring for Hydroelectric Engineering China Three Gorges UniversityYichang 443002China College of Computer and Information Technology China Three Gorges UniversityYichang 443002China Department of Automation Tsinghua UniversityBeijing 100084China

Open data initiatives have promoted governmental agencies and scientific organizations to publish data online for reuse.Research of geoscience focuses on processing georeferenced quantitative data(e.g.,rock parameters,geochemical tests,geophysical surveys and satellite imagery)for discovering new knowledge.Geological knowledge is the cognitive result of human knowledge of the spatial distribution,evolution and interaction patterns of geological objects or processes.Knowledge graphs(KGs)can formalize unstructured knowledge into structured form and have been used in supporting decision-making recently.In this paper,we propose a novel framework that can extract the geological knowledge graph(GKG)from public reports relating to a modelling study.Based on the analysis of basic questions answered by geology,we summarize and abstract geological knowledge elements and then explore a geological knowledge representation model with three levels of“geological conceptsgeological entities-geological relations”to describe semantic units of geological knowledge and their logic relations.Finally,based on the characteristics of mineral resource reports,the geological knowledge representation model oriented to“object relationships”and the hierarchical geological knowledge representation model oriented to“process relationships”are proposed with reference to the commonly used geological knowledge graph representation.The research in this paper can provide some implications for the formalization and structured representation of geological knowledge graphs.

关键词： mineral resource report geological knowledge knowledge graph ontology hierarchical knowledge representation model

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Divergent synthesis of chiral amines via Ni-catalyzed chemo-and enantioselective hydrogenation of alkynone imines

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Science China Chemistry 2023年第11期66卷 3186-3192页

作者： Yuchuan ma kai Liu Lin He Hui Lv Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan School of Chemistry and Chemical EngineeringShihezi UniversityShihezi 832000China Hubei Key Lab on Organic and Polymeric Optoelectronic materials Engineering Research Center of Organosilicon Compounds&MaterialsMinistry of EducationSauvage Center for Molecular SciencesKey Laboratory of Biomedical Polymers of Ministry of Education&College of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China

Ligand-mediated nickel-catalyzed asymmetric hydrogenation of alkynone imines has been achieved. By using Ni(OAc)_2·4H_2O/(S,S)-Ph-BPE complex as a catalyst, the chemo-and enantioselective hydrogenation of alkynone imines occurred efficiently to afford chiral propargyl amines with high yields and excellent enantioselectivities(up to 99% yield, >99% ee), leaving the readily reducible alkynyl group intact. Both the C=N and C≡C bonds of alkynone imines were hydrogenated efficiently in the presence of Ni(OAc)_2·4H_2O and Josiphos SL-J011-1, furnishing unfunctionalized chiral imines efficiently(up to 99% yield, >99% ee).The(Z)-allylamines and(E)-allylamines were also efficiently prepared from alkynone imines by the combination of the different catalytic systems. The preliminary mechanism study revealed that the reduction of alkynone imines was a stepwise process and the C=N bonds were preferably hydrogenated in the complete reduction of alkynone imines. The synthetic utility of this method was demonstrated by its application in the late-stage modification of the antiviral drug Zidovudine and the concise synthesis of chiral dibenzoazepine.

关键词： alkynone imine asymmetric hydrogenation propargyl amine enantioselectivity chiral amine

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Ontology-Based BERT Model for Automated Information Extraction from Geological Hazard Reports

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地球科学学刊:英文版 2023年第5期34卷 1390-1405页

作者： kai Ma Miao Tian Yongjian Tan Qinjun Qiu Zhong Xie Rong Huang Hubei Key Laboratory of Intelligent Vision Based Monitoring for Hydroelectric Engineering China Three Gorges UniversityYichang 443002China College of Computer and Information Technology China Three Gorges UniversityYichang 443002China Hubei Engineering Technology Research Center for Farmland Environment Monitoring China Three Gorges UniversityYichang 443002China School of Computer Science China University of GeosciencesWuhan 430074China Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural ResourcesShenzhen 518034China Beijing Key Laboratory of Urban Spatial Information Engineering Beijing 100045China College of Economics and management China Three Gorges UniversityYichang 443002China

Geological knowledge can provide support for knowledge discovery, knowledge inference and mineralization predictions of geological big data. Entity identification and relationship extraction from geological data description text are the key links for constructing knowledge graphs. Given the lack of publicly annotated datasets in the geology domain, this paper illustrates the construction process of geological entity datasets, defines the types of entities and interconceptual relationships by using the geological entity concept system, and completes the construction of the geological corpus. To address the shortcomings of existing language models(such as Word2vec and Glove) that cannot solve polysemous words and have a poor ability to fuse contexts, we propose a geological named entity recognition and relationship extraction model jointly with Bidirectional Encoder Representation from Transformers(BERT) pretrained language model. To effectively represent the text features, we construct a BERT-bidirectional gated recurrent unit network(BiGRU)-conditional random field(CRF)-based architecture to extract the named entities and the BERT-BiGRU-Attention-based architecture to extract the entity relations. The results show that the F1-score of the BERT-BiGRU-CRF named entity recognition model is 0.91 and the F1-score of the BERT-BiGRU-Attention relationship extraction model is 0.84, which are significant performance improvements when compared to classic language models(e.g., word2vec and Embedding from Language Models(ELMo)).

关键词： ontology BERT model name entity recognition relation extraction knowledge graph

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Experimental and Theoretical Study on the Self-Weight Penetration Velocity of Suction Anchor Foundations in Sand

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China Ocean Engineering 2023年第5期37卷 863-875页

作者： SUN kai ma Hui-huan WANG Fu-ming School of Civil Engineering Sun Yat-Sen University&Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Guangdong Key Laboratory of Oceanic Civil Engineering Guangzhou 510275China

The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which distinguishes it from traditional suction foundations.However,this addition resulted in a relatively high penetration resistance and a shallower penetration depth at the self-weight penetration stage.To mitigate this issue,the current study proposes an optimized design where the end of the suction foundation is sharpened.The installation characteristics of the traditional suction foundation and new suction foundation during self-weight penetration into sand are studied through laboratory tests and theoretical analysis.The flat and sharpened bottom shapes are considered in the traditional and new suction models.The effects of the initial penetration velocity on the initial penetration depth and soil plug and impact cavity characteristics are systematically studied.The results show that the self-weight penetration depth of the foundation with a sharpened bottom is 44.5%deeper than that of the foundation with a flat bottom.There are cavities around the foundation at the self-weight penetration stage,and the penetration depth is overestimated by 15%-30%.Finally,a model for predicting the penetration depth of the new suction foundation is proposed.

关键词： suction foundation self-weight penetration penetration velocity soil plug sharpened bottom

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Effect of particle micro-structure on the electrochemical properties of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode material

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International Journal of Minerals,Metallurgy and materials 2022年第8期29卷 1618-1626页

作者： Zexun Tang Hongqi Ye Xin ma kai Han Hunan Provincial Key Laboratory of Efficient and Clean Utilization of manganese Resources College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China Cathode material Research&Development Department Soundon New Energy Technology Co.Ltd.Xiangtan 411100China

Ni-rich layered material is a kind of high-capacity cathode to meet the requirement of electric vehicles.As for the typical LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) material,the particle formation is significant for electrochemical properties of the cathode.In this work,the structure,morphology,and electrochemical performance of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) secondary particles and single crystals were systematically studied.A lower Ni^(2+)/Ni^(3+)molar ratio of 0.66 and a lower residual alkali content of 0.228wt%were achieved on the surface of the single crystals.In addition,the single crystals showed a discharge capacity of 191.6 mah/g at 0.2 C(~12 mah/g lower than that of the secondary particles)and enhanced the electrochemical stability,especially when cycled at 50℃ and in a wider electrochemical window(between 3.0 and 4.4 V vs.Li+/Li).The LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) secondary particles were suitable for applications requiring high specific capacity,whereas single crystals exhibited better stability,indicating that they are more suitable for use in long life requested devices.

关键词： Ni-rich layered materials single crystal cathode micro-structure lithium-ion battery

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