检索结果-南通市图书馆

Topological Entropy of a Graph Map

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2018年第2期34卷 194-208页

作者： Tai xiang sun Guangxi Key Laboratory Cultivation Base of Cross-border E-commerce Intelligent Information Processing Guangxi University of Finance and Economics

Let G be a graph and f： G → G be a continuous map. Denote by h（f）, P（f）, AP（f）, R（f） and w（x, f） the topological entropy of f, the set of periodic points of f, the set of almost periodic points of f, the set of recurrent points of f and the w-limit set of x under f, respectively. In this paper, we show that the following statements are equivalent：（1） h（f）〉 O. （2） There exists an x ∈ G such that w（x, f） ∩ P（f） ≠θ and w（x, f） is an infinite set. （3） There exists an x ∈ G such that w（x, f） contains two minimal sets. （4） There exist x, y ∈G such that w（x, f） - w（y, f） is an uncountable set andw（y,f）∩w（x,f）≠θ. （5） There exist anx C Gand a closed subset A w（x,f） with f（A） A such that w（x,f） - A is an uncountable set. （6） R（f） - nP（f） ≠θ. （7） f｜P（f） is not pointwise equicontinuous.

关键词： Topological entropy periodic point w-limit set recurrent point

A LINEAR PROGRAMMING MODEL BASED ON NETWORK FLOW FOR PATHWAY INFERENCE

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2010年第5期23卷 971-977页

作者： Xianwen REN xiang-sun ZHANG Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Signal transduction pathways play important roles in various biological processes such as cell cycle, apoptosis, proliferation, differentiation and responses to the external stimuli. Efficient computational methods are of great demands to map signaling pathways systematically based on the interactome and microarray data in the post-genome era. This paper proposes a novel approach to infer the pathways based on the network flow well studied in the operation research. The authors define a potentiality variable for each protein to denote the extent to which it contributes to the objective pathway. And the capacity on each edge is not a constant but a function of the potentiality variables of the corresponding two proteins. The total potentiality of all proteins is given an upper bound. The approach is formulated to a linear programming model and solved by the simplex method. Experiments on the yeast sporulation data suggest this novel approach recreats successfully the backbone of the MAPK signaling pathway with a low upper bound of the total potentiality. By increasing the upper bound, the approach successfully predicts all the members of the Mitogen-activated protein kinases （MAPK） pathway responding to the pheromone. This simple but effective approach can also be used to infer the genetic information processing pathways underlying the expression quantitative trait loci （eQTL） associations, illustrated by the second example.

关键词： Gene expression linear programming network flow pathway inference protein interaction network.

A pyramid-based approach to visual exploration of a large volume of vehicle trajectory data

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2012年第4期6卷 345-353页

作者： Jing sun xiang LI Key Laboratory of Geographical Information Science (Ministry of Education) East China Normal University Shanghai 200062 China

Advances in positioning and wireless commu- nicating technologies make it possible to collect large volumes of trajectory data of moving vehicles in a fast and convenient fashion. These data can be applied to traffic studies. Behind this application, a methodological issue that still requires particular attention is the way these data should be spatially visualized. Trajectory data physically consists of a large number of positioning points. With the dramatic increase of data volume, it becomes a challenge to display and explore these data. Existing commercial software often employs vector-based indexing structures to facilitate the display of a large volume of points, but their performance downgrades quickly when the number of points is very large, for example, tens of millions. In this paper, a pyramid-based approach is proposed. A pyramid method initially is invented to facilitate the display of raster images through the tradeoff between storage space and display time. A pyramid is a set of images at different levels with different resolutions. In this paper, we convert vector-based point data into raster data, and build a grid- based indexing structure in a 2D plane. Then, an image pyramid is built. Moreover, at the same level of a pyramid, image is segmented into mosaics with respect to the requirements of data storage and management. Algorithms or procedures on grid-based indexing structure, image pyramid, image segmentation, and visualization operations are given in this paper. A case study with taxi trajectory data in Shanghai is conducted. Results demonstrate that the proposed method outperforms the existing commercial software.

关键词： large volumes of trajectory data visualization grid-based indexing structure image pyramid

Enhancement of photocatalytic efficiency by in situ fabrication of BiOBr/BiVO_4 surface junctions

维普期刊数据库评论

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 Environmental Sciences 2017年第10期29卷 78-83页

作者： Wenzong Yin xiang sun Wenzhong Wang State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences

Surface junctions between Bi OBr and BiVO4 were synthesized. The BiOBr/BiVO4 with 1 wt.%of Bi OBr exhibited the highest photocatalytic activity in the degradation of Rh B under visible-light irradiation. It was found that the highly efficient adsorption of Rh B molecules via the electrostatic attraction between Br-and cationic ／N（Et）2 group played a key role for the high photocatalytic activities of BiOBr/BiVO4. This efficient adsorption promoted the N-deethylation of Rh B and thus accelerated the photocatalytic degradation of Rh ***, the metal-to-metal charge transfer（MMCT） mechanism was proposed, which revealed the concrete path paved with Bi–O–Bi chains for the carrier migration in BiOBr/BiVO4. The interaction between photoexcited Rh B＊ and the Bi^（3＋） in BiVO4 provided the driving force for the migration of photo-generated carriers along the Bi–O–Bi chains. This work has not only demonstrated the important role of efficient adsorption in the photocatalytic degradation of organic contaminants, but also developed a facile strategy to improve the efficiency of photocatalysts.

关键词： Surface junction Photocatalysis N-deethylation Adsorption efficiency Redox potential

Pretreatment of heterocyclic pesticide wastewater using ultrasonic/ozone combined process

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2011年第5期23卷 725-730页

作者： Zhenglong Xiong xiang Cheng Dezhi sun College of Environmental Science & Engineering Beijing Forestry University Beijing 100083 China

Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe diameter, initial pH and 03 dosage on the COD removal were studied. The results showed that the ultrasonic/O3 process significantly improved the biodegradability and reduced the biological toxicity of the wastewater. The ratio of BODs/COD was increased from 0.03 to 0.55 and the EC50 increased from 11% to 52% under ultrasonic/O3 treatment. Low ultrasonic frequency brought better COD removal. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable. The influences of ultrasonic power and probe diameter were small. With an increase in O3 dosage, COD removal was effectively improved. The optimal operational parameters for the combined process on COD removal were ultrasonic frequency 20 kHz, initial pH 9.00, ultrasonic power 300 W and dosage of O3 454.8 mg/（***）, under which the efficiency of COD removal reached 67.2%.

关键词： heterocyclic pesticide wastewater ultrasonic O3 BOD5/COD biological toxicity

Effects of the tensor force on low-energy heavy-ion fusion reactions:a mini review

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2022年第9期74卷 275-283页

作者： xiang-xiang sun Lu Guo School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

In recent several years,the tensor force,one of the most important components of the nucleon-nucleon force,has been implemented in time-dependent density functional theories and it has been found to influence many aspects of low-energy heavy-ion reactions,such as dissipation dynamics,sub-barrier fusions,and low-lying vibration states of colliding ***,the effects of tensor force on fusion reactions have been investigated from the internuclear potential to fusion crosssections *** this work,we present a mini review on the recent progress on this *** the recent progress of low-energy reaction theories,we will also mention more possible effects of the tensor force on reaction dynamics.

关键词： low-energy heavy-ion collision time-dependent density functional theory ion-ion potential fusion cross sections tensor force

Ergodic Measures of Geodesic Flows on Compact Lie Groups

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2013年第9期29卷 1781-1790页

作者： Gang LIAO Wen xiang sun School of Mathematical Sciences Peking University

Let Ψ be the geodesic flow associated with a two-sided invariant metric on a compact Lie group. In this paper, we prove that every ergodic measure μ of Ψ is supported on the unit tangent bundle of a flat torus. As an application, all Lyapunov exponents of μ are zero hence μ is not hyperbolic. Our underlying manifolds have nonnegative curvature （possibly strictly positive on some sections）, whereas in contrast, all geodesic flows related to negative curvature are Anosov hence every ergodic measure is hyperbolic.

关键词： Geodesic flows entropy compact Lie groups two sided invariant metrics

Jointly optimizing user clustering,power management,and wireless channel allocation for NOMA-based Internet of Things

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2021年第1期7卷 29-36页

作者： xiang sun Liangkun Yu Yin Yang Department of Electrical&Computer Engineering University of New MexicoAlbuquerqueNM87131USA School of Computing Clemson UniversityClemsonSC29634USA

In order to accommodate the large number of Internet of Things(IoT)connections in mobile networks,Non-Orthogonal Multiple Access(NOMA)has been applied as the resource sharing mechanism in mobile access networks to improve the spectrum *** NOMA-based resource management for uplink communications comprises two problems,i.e.,user clustering and power&wireless channel *** clustering refers to assigning users in terms of IoT devices to different clusters(where users in the same cluster are sharing the wireless channels to upload their data),and power&wireless channel allocation is to optimize the transmission power of the users and the number of wireless channels allocated to the users in a *** two problems are coupled together,thus making it difficult to solve the NOMA-based resource management *** this paper,we propose a QoS-aWarE resourcE managemenT(SWEET)for NOMA algorithm to jointly optimize the user clustering,power management,and wireless channel allocation such that the number of wireless channels is minimized and the data rate requirements of the users can be *** performance of SWEET is validated via extensive simulations.

关键词： NOMA Internet of Things Resource management

DETECTING COMMUNITY STRUCTURE： FROM PARSIMONY TO WEIGHTED PARSIMONY

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2010年第5期23卷 1024-1036页

作者： Junhua ZHANG Yuqing QIU xiang-sun ZHANG Key Laboratory of Random Complex Structures and Data Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Community detection has attracted a great deal of attention in recent years. A parsimony criterion for detecting this structure means that as minimal as possible number of inserted and deleted edges is needed when we make the network considered become a disjoint union of cliques. However, many small groups of nodes are obtained by directly using this criterion to some networks especially for sparse ones. In this paper we propose a weighted parsimony model in which a weight coefficient is introduced to balance the inserted and deleted edges to ensure the obtained subgraphs to be reasonable communities. Some benchmark testing examples are used to validate the effectiveness of the proposed method. It is interesting that the weight here can be determined only by the topological features of the network. Meanwhile we make some comparison of our model with maximizing modularity Q and modularity density D on some of the benchmark networks, although sometimes too many or a little less numbers of communities are obtained with Q or D, a proper number of communities are detected with the weighted model. All the computational results confirm its capability for community detection for the small or middle size networks.

关键词： Cliques community detection complex networks parsimony.