检索结果-南通市图书馆

Oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions via Prufer transformation

在线全文

学校读者我要写书评

暂无评论

Applied mathematics(A Journal of Chinese Universities) 2024年第2期39卷 191-200页

作者： LI Zhi-yu LI Kun CAI Jin-ming QIN Jian-fang ZHENG Zhao-wen School of mathematical Sciences Qufu Normal UniversityQufu 273165China College of mathematics and Systems Science Guangdong Polytechnic Normal UniversityGuangzhou 510665China

A class of Sturm-Liouville problems with discontinuity is studied in this *** oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions are *** main method used in this paper is based on Prufer transformation,which is different from the classical ***,we give two examples to verify our main results.

关键词： Sturm-Liouville problem interface condition oscillatory solution

A Global Optimality Principle for Fully Coupled Mean-field Control Systems

在线全文

学校读者我要写书评

暂无评论

Acta mathematicae Applicatae Sinica 2024年第2期40卷 379-413页

作者： Tao HAO School of Statistics and mathematics Shandong University of Finance and EconomicsJinan 250014China

This paper concerns a global optimality principle for fully coupled mean-field control *** the first-order and the second-order variational equations are fully coupled mean-field linear FBSDEs. A new linear relation is introduced, with which we successfully decouple the fully coupled first-order variational equations. We give a new second-order expansion of Y^(ε) that can work well in mean-field framework. Based on this result, the stochastic maximum principle is proved. The comparison with the stochastic maximum principle for controlled mean-field stochastic differential equations is supplied.

关键词： optimal control global maximum principle fully coupled general mean-field FBSDE adjoint equation recursive utility

Enhanced Flexoelectric Response from Functionally Gradient Electrets Undergoing Crumpling Deformation

在线全文

学校读者我要写书评

暂无评论

ACTA MECHANICA SOLIDA SINICA 2024年第1期37卷 82-89页

作者： ma, Jianhua Xu, Jinrui Li, Jun Wang, Binglei Shandong Univ Dept Engn Mech Jinan 250061 Peoples R China

Non-uniform deformation of the dielectric subjected to external forces can induce the flexoelectric effect, a phenomenon that couples electrical polarization to strain gradients. However, limited by the size effects, flexoelectricity is not significant at the macroscale and only becomes catchable at the microscale and nanoscale. In recent work, we obtained a considerable flexoelectric-like response by crumpling the dielectric embedded with charges, i.e., the electret, which significantly improved the flexoelectric effect at the macroscale. In this work, we further optimize the macroscopic performance of the flexoelectric response by applying gradient treatment to the electret films. Specifically, we analytically derive the electromechanical coupling of crumpled electret films with gradients of different thicknesses, charge densities, and Young's moduli as key design variables. It is shown that the gradient-oriented electret film can be tuned to nearly five times that of a uniform electret film.

关键词： Functionally gradient electret Size effects Crumpling Flexoelectric-like response CRYSTALLINE SURFACES

Anomalous valley Hall effect in two-dimensional valleytronic materials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第4期33卷 2-14页

作者：陈洪欣原晓波任俊峰 School of Physics and Electronics Shandong Normal UniversityJinan 250358China Shandong Provincial Engineering and Technical Center of Light manipulations&Institute of materials and Clean Energy Shandong Normal UniversityJinan 250358China

The anomalous valley Hall effect(AVHE)can be used to explore and utilize valley degrees of freedom in materials,which has potential applications in fields such as information storage,quantum computing and *** exists in two-dimensional(2D)materials possessing valley polarization(VP),and such 2D materials usually belong to the hexagonal honeycomb ***,it is necessary to achieve valleytronic materials with VP that are more readily to be synthesized and applicated *** this topical review,we introduce recent developments on realizing VP as well as AVHE through different methods,i.e.,doping transition metal atoms,building ferrovalley heterostructures and searching for ferrovalley ***,2D ferrovalley systems under external modulation are also discussed.2D valleytronic materials with AVHE demonstrate excellent performance and potential applications,which offer the possibility of realizing novel low-energy-consuming devices,facilitating further development of device technology,realizing miniaturization and enhancing functionality of them.

关键词： anomalous valley Hall effect valley polarization valleytronics two-dimensional materials

mathematical Model,Numerical Simulation and Convergence Analysis of a Semiconductor Device Problem with Heat and magnetic Influences

在线全文

学校读者我要写书评

暂无评论

Acta mathematicae Applicatae Sinica 2024年第2期40卷 302-319页

作者： Chang-feng LI Yi-rang YUAN Huai-ling SONG School of Economics Shandong UniversityJinan 250100China Institute of mathematics Shandong UniversityJinan 250100China College of mathematics and Econometrics Hunan UniversityChangsha 410082China

In this paper,the authors discuss a three-dimensional problem of the semiconductor device type involved its mathematical description,numerical simulation and theoretical *** important factors,heat and magnetic influences are *** mathematical model is formulated by four nonlinear partial differential equations(PDEs),determining four major physical *** influences of magnetic fields are supposed to be weak,and the strength is parallel to the *** elliptic equation is treated by a block-centered method,and the law of conservation is *** computational accuracy is improved one *** equations are convection-dominated,thus are approximated by upwind block-centered *** difference can eliminate numerical dispersion and nonphysical *** diffusion is approximated by the block-centered difference,while the convection term is treated by upwind ***,the unknowns and adjoint functions are computed at the same *** characters play important roles in numerical computations of conductor device *** the theories of priori analysis such as energy estimates,the principle of duality and mathematical inductions,an optimal estimates result is *** a composite numerical method is shown for solving this problem.

关键词： three-dimensional conductor device problem with heat and magnetic influences upwind blockcentered differences elemental conservation of mass numerical analysis

A review of the～1600 ma sedimentation,volcanism,and tectono-thermal events in the Singhbhum craton,Eastern India

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2013年第3期4卷 277-287页

作者： Priyanka Chatterjee Shuvabrata De marinah Ranaivoson Rajat mazumder makoto Arima Department of Geology University of Calcutta35 B.C.RoadKolkata 700019India Geological Studies Unit Indian Statistical Institute203 B.T.RoadKolkata 700108India Graduate School of Environment and Information Science Yokohama National University79-7TokiwadaiHodogaya Yokohama 240-8501Japan School of Biology Earth and Environmental SciencesUniversity of New South WalesKensingtonSydney NSW 2052Australia

The Palaeoproterozoic-Mesoproterozoic transition （ -1600 ma） is a significant event in the Earth history as a global thermal perturbation affected the pre-1600 ma landmasses. Like other cratonic blocks of the world, lithospheric thinning, sedimentation, magmatism, metamorphism and crustal melting/anatexis are associated with this significant geological event in the Singhbhum cratonic province of India. This paper is a review of sedimentological, magmatic and tectono-thermal events in the Singhbhum craton at 1600 ma. The Palaeo-Mesoproterozoic sedimentation and volcanism in the Singhbhum craton took place in a terrestrial intracontinental rift setting. The available geochronological data are indicative of late Palaeoproterozoic to Neoproterozoic tectono-thermal events in the Chhotanagpur Granite Gneissic Complex （CGGC）, an east-west trending arcuate belt of granite gneisses, migmatites and metasedi- mentary rocks. A detailed multidisciplinary geo-scientific investigation of the Dalma volcanic belt and the area to its north （Chandil Formation） and further north in CGGC will enable us to constrain the extant surface processes and crust-mantle interactions, the collision events between the North and South Indian cratonic blocks, and the position of India in the Columbia supercontinent.

关键词： Late Palaeoproterozoic Mesoproterozoic Sedimentation Volcanism Geochronology Singhhhum

maternal Preconception Serum Alanine Aminotransferase Levels and Risk of Preterm Birth among Reproductive-Aged Women—China,2013-2017

在线全文

学校读者我要写书评

暂无评论

China CDC weekly 2024年第10期6卷 181-188,I0001页

作者： Chuanyu Zhao Jiajing Jia Hanbin Wu Qin Xu Xinyi Lyu Meiya Liu Xuan Hu Jueming Lei Yuzhi Deng Yuan He Yuanyuan Wang Zuoqi Peng Ya Zhang Hongguang Zhang Qiaomei Wang Haiping Shen Yiping Zhang Donghai Yan Ying Yang Xu ma National Research Institute for Family Planning BeijingChina National Human Genetic Resources Center BeijingChina Graduate School of Peking Union Medical College BeijingChina Department of Epidemiology Fuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina

Summary What is already known about this topic?The significance of maternal liver health concerning preterm birth(PTB)is well recognized;however,there is a gap in understanding the precise influence of preconception s... 详细信息

关键词： Serum precise concerning

A Study of Current Land Use in the Urban Area of ma'anshan City

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Agricultural Research 2016年第4期8卷 58-61,67页

作者： Ning ZHANG Zhongxiang YU College of Economics and management Anhui Agricultural University Institute of Land and Resources Anhui Agricultural University

With the acceleration of urbanization,urban development poses a growing demand for ***'s national conditions of a large population with relatively little arable land require us to intensively use land,and more and more departments have been aware of the importance of intensive urban land *** study on the current land use in the urban area of ma'anshan City,is not only conducive to adjustment of land use layout and structure as well as urban ecological construction,but also of guiding significance to the economical and intensive land use in ma'anshan *** paper first describes the natural,social and economic situation of ma'anshan's urban area,then analyzes the land use structure,layout and problems,and finally puts forth the recommendations for improving current land use situation in the urban area of ma'anshan City.

关键词： Current land use Intensive land use level Urban ecology Recommendations

An Approximation Algorithm Based on Seeding Algorithm for Fuzzy k-Means Problem with Penalties

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of the Operations Research Society of China 2024年第2期12卷 387-409页

作者： Wen-Zhao Liu Min Li School of mathematics and Statistics Shandong Normal UniversityJinan 250014ShandongChina

As a classic NP-hard problem in machine learning and computational geometry,the k-means problem aims to partition the given dataset into k clusters according to the minimal squared Euclidean *** from k-means problem and most of its variants,fuzzy k-means problem belongs to the soft clustering problem,where each given data point has relationship to every center *** to fuzzy k-means problem,fuzzy k-means problem with penalties allows that some data points need not be clustered instead of being paid *** this paper,we propose an O(αk In k)-approximation algorithm based on seeding algorithm for fuzzy k-means problem with penalties,whereαinvolves the ratio of the maximal penalty value to the minimal ***,we implement numerical experiments to show the effectiveness of our algorithm.

关键词： Approximation algorithm.Seeding algorithm Fuzzy k-means problem with penalties