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On contactomorphism group of contact structure overtwisted at infinity on R^3

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Science china mathematics 2007年第8期50卷 1087-1092页

作者： li YU department of mathematics,nanjing university,nanjing 210093.china department of mathematics Nanjing University Nanjing 210093 China

We compute all the homotopy groups of the compactly supported contactomorphism group of a contact structure on R^3 which is overtwisted at infinity.

关键词： contactomorphism overtwisted contact structure

On the 3-rank of tame kernels of certain pure cubic number fields

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Science china mathematics 2010年第9期53卷 2381-2394页

作者： li YuanYuan & QIN HouRong department of mathematics,nanjing university,nanjing 210093.china 1. department of mathematics Nanjing University Nanjing 210093 China

In this paper,we present some explicit formulas for the 3-rank of the tame kernels of certain pure cubic number fields,and give the density results concerning the 3-rank of the tame *** examples are given in Tables 1 ... 详细信息

关键词： the 3-rank of the tame kernels pure cubic fields density

Global dimension and left derived functors of Hom

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Science china mathematics 2007年第6期50卷 887-898页

作者： li-xin MAO & Nan-qing DING Institute of mathematics, nanjing Institute of Technology, nanjing 211167, china department of mathematics, nanjing university, nanjing 210093, china 1. Institute of mathematics Nanjing Institute of Technology Nanjing 211167 China 2. department of mathematics Nanjing University Nanjing 210093 China

It is well known that the right global dimension of a ring R is usually computed by the right derived functors of Hom and the left projective resolutions of right R-modules. In this paper, for a left coherent and right perfect ring R, we characterize the right global dimension of R, from another point of view, using the left derived functors of Hom and the right projective resolutions of right R-modules. It is shown that rD(R) ? n (n ? 2) if and only if the gl right Proj-dim M R ? n?2 if and only if Ext n?1(N,M) = 0 for all right R-modules N and M if and only if every (n?2)th Projcosyzygy of a right R-module has a projective envelope with the unique mapping property. It is also proved that rD(R) ? n (n ? 1) if and only if every (n?1)th Proj-cosyzygy of a right R-module has an epic projective envelope if and only if every nth Proj-cosyzygy of a right R-module is projective. As corollaries, the right hereditary rings and the rings R with rD(R) ? 2 are characterized.

关键词： global dimension projective resolution envelope 16E10 16E30 16E05

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On c-equivalence

Science china mathematics 2009年第12期52卷 2389-2396页

作者： li xia department of mathematics,nanjing university,nanjing 210093.china 1. department of mathematics Nanjing University Nanjing 210093 China

In this paper,we propose some c-equivalence specifically for autonomous Lagrangian systems and show how to construct connecting orbits in energy surface based on this c-equivalence.

关键词： c-equivalence autonomous Lagrangian systems connecting orbits 37K14

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Variational construction of unbounded orbits in Lagrangian systems

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Science china mathematics 2010年第3期53卷 617-624页

作者： CHENG Chong-Qing 1, & li xia 2 1 department of mathematics, nanjing university, nanjing 210093, china 2 department of mathematics, Suzhou university of Science and Technology, Suzhou 215001, china 1. department of mathematics Nanjing University Nanjing 210093 China2. Department of Mathematics Suzhou University of Science and Technology Suzhou 215001 China

We show the existence of unbounded orbits in perturbations of generic geodesic flow in T2 by a generic periodic potential. Different from previous work such as in Mather (1997), the initial values of the orbits obtain... 详细信息

关键词： positive definite Lagrangian variational method unbounded orbit

A regularization algorithm of dynamic light scattering for estimating the particle size distribution of dual-substance mixture in water

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Particuology 2024年第6期89卷 246-257页

作者： Yanghong Wang Ziqiang Meng Zipei Zhang Min xia li xia Wei li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China

Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal ***,current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion *** this study,we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle *** algorithm retrieves the particle size distributions of two substances,respectively,by taking advantage of their refractive index *** simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°.Instead of the original identity matrix,the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm,which obviously improves the anti-interference,accuracy,and stability of the ***,the inversion of particle size distribution is carried out at a 0.01%–1%noise level,which shows that the algorithm has an available antinoise ***,experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.

关键词： Dynamic light scattering Dual-substance mixture Particle sized istribution Tikhnonov regularization

Formation and evolution of X-ray binaries

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 9-13页

作者： li xiangDong department of Astronomy,nanjing university,nanjing 210093.china 1. department of Astronomy Nanjing University Nanjing 210093 China

We review recent progress in theoretical understanding of X-ray binaries,which has largely been driven by new *** select several topics including formation of compact low-mass X-ray binaries,the evolutionary connection between low-mass X-ray binaries and binary and millisecond radio pulsars,and ultraluminous X-ray sources,to illustrate the interplay between theories and observations.

关键词： X-ray binaries pulsars mass transfer stellar evolution

light-based 3D printing of stimulus-responsive hydrogels forminiature devices:recent progress and perspective

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Bio-Design and Manufacturing 2024年第5期7卷 721-746页

作者： Chen Xin Neng xia li Zhang department of Mechanical and Automation Engineering The Chinese University of Hong KongHong Kong 999077China Multi-Scale Medical Robotics Center Hong Kong Science ParkShatin NTHong Kong 999077China Chow Yuk Ho Technology Center for Innovative Medicine The Chinese University of Hong KongHong Kong 999077China department of Surgery The Chinese University of Hong KongHong Kong 999077China CUHK T Stone Robotics Institute The Chinese University of Hong KongHong Kong 999077China

Miniature devices comprising stimulus-responsive hydrogels with high environmental adaptability are now considered competitive candidates in the fields of biomedicine,precise sensors,and tunable *** and advanced fabricationmethods are critical formaximizing the application capabilities ofminiature ***-based three-dimensional(3D)printing technology offers the advantages of a wide range of applicable materials,high processing accuracy,and strong 3D fabrication capability,which is suitable for the development of miniature devices with various *** paper summarizes and highlights the recent advances in light-based 3D-printed miniaturized devices,with a focus on the latest breakthroughs in lightbased fabrication technologies,smart stimulus-responsive hydrogels,and tunable miniature devices for the fields of miniature cargo manipulation,targeted drug and cell delivery,active scaffolds,environmental sensing,and optical ***,the challenges in the transition of tunable miniaturized devices from the laboratory to practical engineering applications are *** opportunities that will promote the development of tunable microdevices are elaborated,contributing to their improved understanding of these miniature devices and further realizing their practical applications in various fields.

关键词： 3D printing Stimulus-responsive hydrogels Miniature devices Shape-morphing

Nonlinear ergodic theorem for semitopological semigroups of non-lipschitzian mappings in Banach spaces

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Chinese Science Bulletin 1997年第1期42卷 8-11页

作者： li Gang and MA Jipu1. department of mathematics, Yangzhou Normal College, Yangzhou 225002, china 2. department of mathematics, nanjing university, nanjing 210093, china department of mathematics Yangzhou Normal College Yangzhou China department of mathematics Nanjing University Nanjing China

LET G be a semitopological semigroup, i. e. G is a semigroup with a Hausdorff topology such that for each s∈G the mapping s|→s·t and s|→t·s from G to G are continuous. G is called right reversible if any two closed left ideals of G have non-void intersection. In this case, (G,≤) is a directed system when the binary relation '≤' on G is defined by a≤b if and only if Let E be the uniformly convex Banach space

关键词： nonlinear semigroup ergodic theorem non-lipschitzian mapping.