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A note on Pythagorean hodograph quartic spiral

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Applied Mathematics(A Journal of Chinese Universities) 2018年第2期33卷 234-252页

作者： ZHENG Zhi-hao WANG Guo-zhao school of mathematical sciences Zhejiang University

By using the geometric constraints on the control polygon of a Pythagorean hodo- graph （PH） quartic curve, we propose a sufficient condition for this curve to have monotone curvature and provide the detailed proof. Based on the results, we discuss the construction of spiral PH quartic curves between two given points and formulate the transition curve of a G2 contact between two circles with one circle inside another circle. In particular, we deduce an attainable range of the distance between the centers of the two circles and summarize the algorithm for implementation. Compared with the construction of a PH quintic curve, the complexity of the solution of the equation for obtaining the transition curves is reduced.

关键词： Pythagorean hodograph quartic curve spiral curvature transition curve

Complete convergence for arrays of rowwise negatively superadditive-dependent random variables and its applications

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Applied Mathematics(A Journal of Chinese Universities) 2016年第4期31卷 439-457页

作者： WU Yi WANG Xue-jun HU Shu-he school of mathematical sciences Anhui University

In this paper, an exponential inequality for the maximal partial sums of negatively superadditive-dependent （NSD, in short） random variables is established. By uSing the exponen- tial inequality, we present some general results on the complete convergence for arrays of rowwise NSD random variables, which improve or generalize the corresponding ones of Wang et al. [28] and Chen et al. [2]. In addition, some sufficient conditions to prove the complete convergence are provided. As an application of the complete convergence that we established, we further investigate the complete consistency and convergence rate of the estimator in a nonparametric regression model based on NSD errors.

关键词： exponential inequality, complete convergence, negatively superadditive-dependent random vari-ables nonparametric regression model, complete consistency.

Influence of lithospheric thickness distribution on oil and gas basins,China seas and adjacent areas

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Acta Oceanologica Sinica 2024年第4期43卷 1-14页

作者： Jing Ma Wanyin Wang Hermann Zeyen Yimi Zhang Zhongsheng Li Tao He Dingding Wang school of Geology Engineering and Geomatics Key Laboratory of Western China’s Mineral Resources and Geological Engineering of Ministry of EducationChang’an UniversityXi’an 710054China UMR8148 GEOPS CNRS/UniversitéParis-SaclayDépartement des Sciences de la TerreBât.50491405France CNOOC Research Institute Co. Ltd.Beijing 100027China Qingdao Institute of marine geology Qingdao 266071China Department of Earth sciences Memorial University of NewfoundlandSt.John’sNewfoundland AlB3X5Canada university of Naples Federico Ⅱ Department of Earth SciencesNaples80138Italy

The distribution of oil and gas resources is intricately connected to the underlying structure of the ***,investigating the characteristics of lithospheric thickness and its correlation with oil and gas basins is highly *** research utilizes recently enhanced geological–geophysical data,including topographic,geoid,rock layer thickness,variable rock layer density,and interface depth *** the principles of lithospheric isostasy and heat conduction,we compute the laterally varying lithospheric thickness in the China seas and adjacent *** these results,two pivotal parameters for different types of oil and gas basins were statistically analyzed:the minimum lithospheric thickness and the relative fluctuation in lithospheric thickness.A semiquantitative analysis was used to explore the connection between these parameters and the hydrocarbon abundance within the oil and gas *** study unveils distinct variations in lithospheric thickness among basins,with oil and gas rich basins exhibiting a thicker lithosphere in the superimposed basins of central China and a thinner lithosphere in the rift basins of eastern ***,the relative fluctuations in lithospheric thickness in basins demonstrate significant disparities:basins rich in oil and gas often exhibit greater thickness ***,in the offshore basins of China,a conspicuous negative linear correlation is observed between the minimum lithospheric thickness and the relative fluctuation in lithospheric *** study posits that deep-seated thermal upwelling results in lithospheric undulations and extensional thinning in oil and gas ***,sustained deep-seated heat influences sedimentary materials in basins,creating favorable conditions for oil and gas *** insights derived from this study contribute to a quantitative understanding of the intricate relationships between deep lithospheric structures and oil and gas basins.

关键词： China seas and adjacent areas lithospheric thickness oil and gas basins

Characterization of local chemical ordering and deformation behavior in high entropy alloys by transmission electron microscopy

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 877-886页

作者： Qiuhong Liu Qing Du Xiaobin Zhang Yuan Wu Andrey A.Rempel Xiangyang Peng Xiongjun Liu Hui Wang Wenli Song Zhaoping Lü Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China school of Materials Science and Engineering Ocean University of ChinaQingdao 266100China Institute of Metallurgy of the Ural Branch of the Russian Academy of sciences Ekaterinburg 620016Russia China Nuclear Power Technology Research Institute Co.Ltd. Shenzhen 518000China Institute of High Energy Physics Chinese Academy of Sciences(CAS)Beijing 100049China Spallation Neutron Source Science Center Dongguan 523803China

Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed compositions,and varied *** electron microscopy(TEM)as well as its aberration correction techniques are powerful for characterizing SROs in these compositionally complex *** this short communication,we summarized recent progresses regarding characterization of SROs using TEM in the field of *** using advanced TEM techniques,not only the existence of SROs was confirmed,but also the effect of SROs on the deformation mechanism was ***,the perspective related to application of TEM techniques in HEAs are also discussed.

关键词： high entropy alloys transmission electron microscopy short-range ordering deformation mechanisms

The State Equations Methods for Stochastic Control Problems

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Numerical Mathematics(Theory,Methods and Applications) 2010年第1期3卷 79-96页

作者： Lijin Wang Fengshan Bai Department of mathematical sciences Tsinghua University Beijing 100084China. school of mathematical sciences Graduate University of Chinese Academy of Sciences Beijing 100049 China.

The state equations of stochastic control problems,which are controlled stochastic differential equations,are proposed to be discretized by the weak midpoint rule and predictor-corrector methods for the Markov chain approximation approach. Local consistency of the methods are *** tests on a simplified Merton's portfolio model show better simulation to feedback control rules by these two methods, as compared with the weak Euler-Maruyama discretisation used by *** suggests a new approach of improving accuracy of approximating Markov chains for stochastic control problems.

关键词： Stochastic optimal control Markov chain approximation Euler-Maruyama discretisation midpoint rule predictor-corrector methods portfolio management.

An Evidence-Based CoCoSo Framework with Double Hierarchy Linguistic Data for Viable Selection of Hydrogen Storage Methods

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Computer Modeling in Engineering & sciences 2024年第3期138卷 2845-2872页

作者： Raghunathan Krishankumar Dhruva Sundararajan K.S.Ravichandran Edmundas Kazimieras Zavadskas Information Technology Systems and Analytics Area Indian Institute of Management Bodh GayaBodh GayaBihar824234India Department of Mathematics Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatore641112India Institute of Sustainable Construction Vilnius Gediminas Technical UniversityVilnius10223Lithuania

Hydrogen is the new age alternative energy source to combat energy demand and climate *** of hydrogen is vital for a nation’s *** of literature provide different methods for storing the produced hydrogen,and the rational selection of a viable method is crucial for promoting sustainability and green ***,hydrogen storage is associated with diverse sustainable and circular economy(SCE)*** a result,the authors consider the situation a multi-criteria decision-making(MCDM)*** infer that previous models for hydrogen storage method(HSM)selection(i)do not consider preferences in the natural language form;(ii)weights of experts are not methodically determined;(iii)hesitation of experts during criteria weight assessment is not effectively explored;and(iv)three-stage solution of a suitable selection of HSM is *** by these gaps,in this paper,authors put forward a new integrated framework,which considers double hierarchy linguistic information for rating,criteria importance through inter-criteria correlation(CRITIC)for expert weight calculation,evidence-based Bayesian method for criteria weight estimation,and combined compromise solution(CoCoSo)for ranking *** applicability of the developed framework is testified by using a case example of HSM selection in *** and comparative analysis reveal the merits and limitations of the developed framework.

关键词： Hydrogen storage methods double hierarchy hesitant fuzzy linguistic term set evidence theory CoCoSo method sustainability circular economy

Piezotronic neuromorphic devices:principle,manufacture,and applications

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International Journal of Extreme Manufacturing 2024年第3期6卷 363-385页

作者： Xiangde Lin Zhenyu Feng Yao Xiong Wenwen Sun Wanchen Yao Yichen Wei Zhong Lin Wang Qijun Sun Department of Research Shanghai University of Medicine and Health Sciences Affiliated Zhoupu HospitalShanghai 201318People’s Republic of China Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400People’s Republic of China Center on Nanoenergy Research School of Chemistry and Chemical EngineeringGuangxi UniversityNanning 530004People’s Republic of China Shandong Zhongke Naneng Energy Technology Co. LtdDongying 257061People’s Republic of China Georgia Institute of Technology AtlantaGA 30332-0245United States of America

With the arrival of the era of artificial intelligence(AI)and big data,the explosive growth of data has raised higher demands on computer hardware and *** techniques inspired by biological nervous systems are expected to be one of the approaches to breaking the von Neumann *** neuromorphic devices modulate electrical transport characteristics by piezopotential and directly associate external mechanical motion with electrical output signals in an active manner,with the capability to sense/store/process information of external *** this review,we have presented the piezotronic neuromorphic devices(which are classified into strain-gated piezotronic transistors and piezoelectric nanogenerator-gated field effect transistors based on device structure)and discussed their operating mechanisms and related manufacture ***,we summarized the research progress of piezotronic neuromorphic devices in recent years and provided a detailed discussion on multifunctional applications,including bionic sensing,information storage,logic computing,and electrical/optical artificial ***,in the context of future development,challenges,and perspectives,we have discussed how to modulate novel neuromorphic devices with piezotronic effects more *** is believed that the piezotronic neuromorphic devices have great potential for the next generation of interactive sensation/memory/computation to facilitate the development of the Internet of Things,AI,biomedical engineering,etc.

关键词： piezotronics neuromorphic devices strain-gated transistors piezoelectric nanogenerators synaptic transistors

Evolution history dominantly regulates fine root lifespan in tree species across the world

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Forest Ecosystems 2024年第4期11卷 516-525页

作者： Xingzhao Huang Zhouying Lu Fangbing Li Yang Deng Fangfang Wan Quancheng Wang Fousseni Folega Jinsong Wang Zijian Guo Anhui Province Key Laboratory of Forest Resources and Silviculture Anhui Agricultural UniversityHefei 230036China State Key Laboratory of Subtropical Silviculture Zhejiang A&F UniversityHangzhou 311300China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Laboratory of Botany and Plant Ecology(LBEV) University of LomeTogo01PoBox 1515LomeTogo State Key Laboratory of Efficient Production of Forest Resources Beijing Forestry UniversityBeijing 100083China school of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China

Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ***,the general patterns and determinants of forest fine root lifespan at the global scale are still *** compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan ***,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than *** root lifespan was longer for evergreens than deciduous ***(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)*** different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical *** root lifespan increased with soil depth and root ***,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker *** results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental *** findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.

关键词： Fine root lifespan Trees Phylogeny Root order Soil property Climatic factors

Investigation and mitigation of Mott neuronal oscillation fluctuation in spiking neural network

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Science China(Information sciences) 2024年第2期67卷 291-301页

作者： Lindong WU Zongwei WANG Lin BAO Linbo SHAN Zhizhen YU Yunfan YANG Shuangjie ZHANG Guandong BAI Cuimei WANG John ROBERTSON Yuan WANG Yimao CAI Ru HUANG school of Integrated Circuits Peking University Beijing Advanced Innovation Center for Integrated Circuits State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Department of Engineering University of Cambridge

Mott devices, featuring low hardware cost and high energy efficiency, have been demonstrated as a key oscillatory element in artificial neurons to enable spiking neural networks(SNNs) such as conversionbased SNNs(CSNNs). However, there will be inevitably non-ideal fluctuation in the oscillation behavior,causing the accuracy degradation of networks. In this paper, we investigate the Mott neuronal oscillation fluctuation(NOF) through experiments and modeling. The results show that the NOF phenomenon conforms to Gaussian distribution and originates from thermal fluctuation induced switching voltage variations. We construct a two-layer CSNN for image recognition tasks to study the NOF effect and propose the activation function boundary(AFB) method to strengthen the stability of the network. The results indicate that AFB can improve the accuracy of CSNN by up to 15.5% by tightening output distribution.

关键词： Mott neuron oscillation fluctuation variation-aware Mott neuronal model conversion-based spiking neural network activation function boundary