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Improving the Angular Resolution of Coded-Mask Telescopes by Direct Demodulation

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Chinese Journal of Astronomy and Astrophysics 2008年第3期8卷 343-348页

作者： Zong-Jun Shen jian-feng Zhou Department of Engineering Physics and Center for Astrophysics Tsinghua University Beijing 100084 China

We develop a new procedure to improve the angular resolution of coded-mask telescopes by the Direct Demodulation Method （DDM）. DDM has been applied to both real and simulated data of INTEGRAL/IBIS. The angular resol... 详细信息

关键词： instrumentation coded-mask -- telescopes INTEGRAL/IBIS -- techniques high angular resolution-methods direct demodulation

Position-Aware and Subgraph Enhanced Dynamic Graph Contrastive Learning on Discrete-Time Dynamic Graph

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Computers, Materials & Continua 2024年第11期81卷 2895-2909页

作者： jian feng Tian Liu Cailing Du College of Computer Science&Technology Xi’an University of Science and TechnologyXi’an710054China

Unsupervised learning methods such as graph contrastive learning have been used for dynamic graph represen-tation learning to eliminate the dependence of ***,existing studies neglect positional information when learning discrete snapshots,resulting in insufficient network topology *** the same time,due to the lack of appropriate data augmentation methods,it is difficult to capture the evolving patterns of the network *** address the above problems,a position-aware and subgraph enhanced dynamic graph contrastive learning method is proposed for discrete-time dynamic ***,the global snapshot is built based on the historical snapshots to express the stable pattern of the dynamic graph,and the random walk is used to obtain the position representation by learning the positional information of the ***,a new data augmentation method is carried out from the perspectives of short-term changes and long-term stable structures of dynamic ***,subgraph sampling based on snapshots and global snapshots is used to obtain two structural augmentation views,and node structures and evolving patterns are learned by combining graph neural network,gated recurrent unit,and attention ***,the quality of node representation is improved by combining the contrastive learning between different structural augmentation views and between the two representations of structure and *** results on four real datasets show that the performance of the proposed method is better than the existing unsupervised methods,and it is more competitive than the supervised learning method under a semi-supervised setting.

关键词： Dynamic graph representation learning graph contrastive learning structure representation position representation evolving pattern

Complete Hypersurfaces with Constant Laguerre Scalar Curvature in R^n

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Acta Mathematica Sinica,English Series 2016年第6期32卷 715-724页

作者： jian Bo FANG feng jiang LI School of Mathematics and Statistics Chuxiong Normal University Department of Mathematics Yunnan Normal University

Let x ： M^n-1→ R^n be an umbilical free hypersurface with non-zero principal curvatures. Two basic invariants of M under the Laguerre transformation group of Rn are Laguerre form C and Laguerre tensor L. In this paper, we prove the following theorem： Let M be an （n-1）-dimensional （n 〉 3） complete hypersurface with vanishing Laguerre form and with constant Laguerre scalar curvature R in R^n, denote the trace-free Laguerre tensor by L = L -1/n-1tr（L）· Id. If supM ｜｜L｜｜=0,then M is Laguerre equivalent to a Laguerre isotropic hypersurface; and if supM ｜｜L^-｜｜≡√（n-1）（n-2）R/ （n-1）（n-2）（n-3） , M isLaguerre equivalent to the hypersurface x^- ： H^1× S^n-2 → R^n.

关键词： Laguerre isoparametric hypersurface Laguerre second fundamental form Laguerre metric Laguerre form parallel Laguerre form

Every Toroidal Graph Is Acyclically 8-Choosable

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Acta Mathematica Sinica,English Series 2014年第2期30卷 343-352页

作者： jian feng HOU Gui Zhen LIU Center for Discrete Mathematics Fuzhou University School of Mathematics Shandong University

A proper coloring of a graphG is acyclic if G contains no 2-colored cycle.A graph G is acyclically L-list colorable if for a given list assignment L={L（v）：v∈V（G）},there exists a proper acyclic coloringφof G such thatφ（v）∈L（v）for all v∈V（G）.If G is acyclically L-list colorable for any list assignment L with｜L（v）｜≥k for all v∈V（G）,then G is acyclically *** this article,we prove that every toroidal graph is acyclically 8-choosable.

关键词： Acyclic coloring choosability toroidal graph

Research on the inversion of elemental abundances from Chang'E-2 X-ray spectrometry data

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Chinese Journal Of Geochemistry 2014年第3期33卷 289-299页

作者： ban Chao ZHENG Yongchun ZHU Yongchao ZHANG feng XU Lin ZOU Yongliao National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences Space Science Institute Macao University of Science and Technology

The elemental abundances of lunar surface are the important clues to study the formation and evolution history of the Moon. In 2010, China's Chang'E-2(CE-2) lunar orbiter carried a set of X-ray spectrometer(XRS) to investigate the elemental abundances of the lunar surface. During CE-2's life span around the Moon, the XRS experienced several events of solar flare. The X-ray solar monitor onboard recorded the spectra of solar X-rays at the same time. In this paper, we introduced the XRS instrument and data product. We analyzed the characteristics of the XRS data. Using the data obtained during an M solar flare event which had occurred on Feb. 16, 2011, we derived the elemental abundances of Mg, Al, Si, Ca and Fe of the lunar surface in the Oceanus Procellarum. Finally, we discussed the factors that influence the accuracy of the inversion.

关键词： X射线光谱元素丰度数据反演月球表面太阳耀斑月球探测器演化历史数据产品

A family of solutions of the time–space fractional longitudinal wave equation

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Communications in Theoretical Physics 2023年第7期75卷 81-85页

作者： jian-Gen Liu Yi-Ying feng School of Mathematics and Statistics Changshu Institute of TechnologyChangshu 215500JiangsuChina School of Mathematics and Statistics Suzhou UniversitySuzhou 234000AnhuiChina School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116JiangsuChina

In this article,we have studied a nonlinear time–space fractional longitudinal wave equation in the context of the conformable fractional *** the soliton ansatz method and a direct integration approach with the symmetry condition,new soliton and solitary wave solutions are ***,the existing conditions of these obtained solutions are also given in this *** new results add to the existing *** believe that they can provide a new window into the understanding of this model.

关键词： time-space fractional longitudinal wave equation conformable fractional derivative symmetry condition

An Iterative Rounding 2-approximation Algorithm for the k-partial Vertex Cover Problem

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Acta Mathematicae Applicatae Sinica 2014年第2期30卷 271-278页

作者： jian-hua TU Jun-feng DU feng-mei YANG School of Science Beijing University of Chemical Technology

We study a generalization of the vertex cover problem. For a given graph with weights on the vertices and an integer k, we aim to find a subset of the vertices with minimum total weight, so that at least k edges in the graph are covered. The problem is called the k-partial vertex cover problem. There are some 2-approximation algorithms for the problem. In the paper we do not improve on the approximation ratios of the previous algorithms, but we derive an iterative rounding algorithm. We present our technique in two algorithms. The first is an iterative rounding algorithm and gives a （2 ＋ Q/OPT ）-approximation for the k-partial vertex cover problem where Q is the largest finite weight in the problem definition and OPT is the optimal value for the instance. The second algorithm uses the first as a subroutine and achieves an approximation ratio of 2.

关键词： approximation algorithm iterative rounding k-partial vertex cover combinatorial optimization

Strategies and Methods for Cloud Migration

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International Journal of Automation and computing 2014年第2期11卷 143-152页

作者： Jun-feng Zhao jian-Tao Zhou College of Computer Science Inner Mongolia University

Legacy system migration to the cloud brings both great challenges and benefits, so there exist various academic research and industrial applications on legacy system migration to the cloud. By analyzing the research achievements and application status,we divide the existing migration methods into three strategies according to the cloud service models integrally. Different processes need to be considered for different migration strategies, and different tasks will be involved accordingly. The similarities and differences between the migration strategies are discussed, and the challenges and future work about legacy system migration to the cloud are proposed. The aim of this paper is to provide an overall presentation for legacy system migration to the cloud and identify important challenges and future research directions.

关键词： Migration legacy system cloud infrastructure as a service(IaaS) platform as a service(PaaS) software as a service(SaaS).

Modeling Price-Aware Session-Based Recommendation Based on Graph Neural Network

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Computers, Materials & Continua 2023年第7期76卷 397-413页

作者： jian feng Yuwen Wang Shaojian Chen College of Computer Science&Technology Xi’an University of Science and TechnologyXi’an710600China

Session-based Recommendation(SBR)aims to accurately recom-mend a list of items to users based on anonymous historical session *** methods for SBR suffer from several limitations:SBR based on Graph Neural Network often has information loss when constructing session graphs;Inadequate consideration is given to influencing factors,such as item price,and users’dynamic interest evolution is not taken into account.A new session recommendation model called Price-aware Session-based Recommendation(PASBR)is proposed to address these *** constructs session graphs by information lossless approaches to fully encode the original session information,then introduces item price as a new factor and models users’price tolerance for various items to influence users’*** addition,PASBR proposes a new method to encode user intent at the item category level and tries to capture the dynamic interest of users over ***,PASBR fuses the multi-perspective features to generate the global representation of users and make a ***,the intent,the short-term and long-term interests,and the dynamic interests of a user are *** on two real-world datasets show that PASBR can outperform representative baselines for SBR.

关键词： Session-based recommendation graph neural network price-aware intention dynamic interest