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Symmetries and symmetry reductions of the combined KP3 and KP4 equation

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Communications in Theoretical Physics 2023年第1期75卷 15-20页

作者： fa-ren Wang S Y Lou School of Physical Science and Technology Ningbo UniversityNingbo315211China

To find symmetries,symmetry groups and group invariant solutions are fundamental and significant in nonlinear *** this paper,the finite point symmetry group of the combined KP3 and KP4(CKP34)equation is found by means of a direct *** related point symmetries can be obtained simply by taking the infinitesimal form of the finite point symmetry *** point symmetries of the CKP34 equation constitute an infinite dimensional KacMoody-Virasoro *** point symmetry invariant solutions of the CKP34 equation are obtained via the standard classical Lie point symmetry method.

关键词： symmetry reduction integrable system Lie algebra

Irreducible Weight Modules with a Finite-Dimensional Weight Space over the Twisted N z 1 SchrSdinger-Neveu- Schwarz Algebra

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Algebra Colloquium 2017年第4期24卷 697-704页

作者： Huanxia fa Jianzhi Han Junbo Li School of Mathematics and Statistics Qingdao University Qingdao Shandong 266071 China School of Mathematics and Statistics Changshu Institute of Technology Changshu Jiangsu 215500 China School of Mathematical Sciences Tongji University Shanghai 200092 China School of Mathematics and Statistics Qingdao University Qingdao Shandong 266071 China

It is shown that there are no simple mixed modules over the twisted N = 1 Schrodinger-Neveu-Schwarz algebra, which implies that every irreducible weight module over it with a non-trivial finite-dimensional weight spac... 详细信息

关键词： twisted N = 1 Schrodinger-Neveu-Schwarz algebra weight module irre-ducible module

CBMO Estimates for Multilinear Hardy Operators

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Acta Mathematica Sinica,English Series 2010年第7期26卷 1245-1254页

作者： Shah Zhen LU fa You ZHAO School of Mathematical Sciences Beijing Normal University Beijing 100875 P. R. China

The purpose of this paper is to study the multilinear Hardy operators in higher dimensional cases and establish the CBMO estimates for multilinear Hardy operators on some function spaces, such as the Lebesgue spaces, ... 详细信息

关键词： multilinear Hardy operator central BMO space Herz space Morrey-Herz space

SHARAD study on the structures and permittivity of a buried impact crater in Martian Central Elysium Planitia

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Science China Earth Sciences 2023年第11期66卷 2452-2462页

作者： Peng faNG Wenzhe fa Jinhai ZHANG Yangting LIN Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Engineering Laboratory for Deep Resources Equipment and Technology Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100029China Institute of Remote Sensing and Geographical Information System School of Earth and Space SciencesPeking UniversityBeijing 100871China

The Elysium Planitia,located in the transition zone between the northern and southern hemispheres,is one of the key areas for studying the stratigraphic structure and geological history of *** studies have shown that this plain has undergone complex surface modification processes including fluvial and volcanic processes,and systematic progress has been made in the study of macro-geological ***,there are relatively few studies on the regional structure of the plain,which restricts our understanding of the regional geological processes.A buried impact crater in the central part of the Elysium Planitia could have recorded the surface modification process since the formation of the impact crater,however,it is difficult to distinguish the subsurface stratigraphy due to the weak orbital radar reflection *** this study,we denoised Shallow Radar data and obtained a radargram with clear subsurface *** estimated the permittivity of subsurface materials via a multilayer reflection *** results show that two subsurface reflectors divide the structure of the buried impact crater into three layers(overlying layer,underlying layer,and bottom layer).The shallow subsurface reflector covers almost the whole impact crater,while the deep subsurface reflector covers only the southwest part of the impact *** the permittivity inversion results with the geological background of lava activity in the Elysium Planitia area,we argue that the overlying layer may be a mixture of regolith and lava flow with low density,while the underlying layer and bottom layer are dense lava *** reflector between the underlying layer and bottom layer is probably a thin deposit derived from weathering between two lava activities,and its possible formation mechanism is as follows:the crater rim and peripheral ejecta has undergone relatively strong wind erosion and the eroded material was transport to the southwestern part of the impact crater,forming

关键词： Mars Elysium Planitia SHARAD Buried crater Permittivity inversion

The Derivation Algebra and Automorphism Group of the Twisted N = 2 Superconformal Algebra

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Algebra Colloquium 2016年第3期23卷 443-454页

作者： Huanxia fa Jianzhi Han Xiaoqing Yue School of Mathematics and Statistics Changshu Institute of Technology Changshu Jiangsu 215500 China Department of Mathematics Tongji University Shanghai 200092 China Department of Mathematics Sichuan University Chengdu 610064 China

In this paper, the derivation algebra and the automorphism group of the twisted N = 2 superconformal algebra are completely determined.

关键词： twisted N = 2 superconformal algebra derivation algebras automorphismgroups

Designing a location update strategy for free-moving and network-constrained objects with varying velocity

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第8期15卷 675-686页

作者： Yuan-Ko HUANG Lien-fa LIN Department of Information Communication Kao-Yuan University

Spatio-temporal databases aim at appropriately managing moving objects so as to support various types of queries. While much research has been conducted on developing query processing techniques, less effort has been made to address the issue of when and how to update location information of moving objects. Previous work shifts the workload of processing updates to each object which usually has limited CPU and battery capacities. This results in a tremendous processing overhead for each moving object. In this paper, we focus on designing efficient update strategies for two important types of moving objects, free-moving objects(FMOs) and network-constrained objects(NCOs), which are classified based on object movement models. For FMOs, we develop a novel update strategy, namely the FMO update strategy(FMOUS), to explicitly indicate a time point at which the object needs to update location information. As each object knows in advance when to update(meaning that it does not have to continuously check), the processing overhead can be greatly reduced. In addition, the FMO update procedure(FMOUP) is designed to efficiently process the updates issued from moving objects. Similarly, for NCOs, we propose the NCO update strategy(NCOUS) and the NCO update procedure(NCOUP) to inform each object when and how to update location information. Extensive experiments are conducted to demonstrate the effectiveness and efficiency of the proposed update strategies.

关键词： Spatio-temporal databases Moving objects Free-moving objects Network-constrained objects

Constraining Dark Energy and Cosmological Transition Redshift with Type Ia Supernovae

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Chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 561-571页

作者： fa-Yin Wang Zi-Gao Dai Department of Astronomy Nanjing University Nanjing 210093

The property of dark energy and the physical reason for the acceleration of the present universe are two of the most difficult problems in modern cosmology. The dark energy contributes about two-thirds of the critical density of the present universe from the observations of type-Ia supernovae （SNe Ia） and anisotropy of cosmic microwave background （CMB）. The SN Ia observations also suggest that the universe expanded from a deceleration to an acceleration phase at some redshift, implying the existence of a nearly uniform component of dark energy with negative pressure. We use the ＂Gold＂ sample containing 157 SNe Ia and two recent well-measured additions, SNe Ia 1994ae and 1998aq to explore the properties of dark energy and the transition redshift. For a fiat universe with the cosmological constant, we measure ΩM=0.28-0.05^＋0.04 which is consistent with Riess et al. The transition redshift is zT=0.60-0.08^＋0.04. We also discuss several dark energy models that define w（z） of the parameterized equation of state of dark energy including one parameter and two parameters （w（z） being the ratio of the pressure to energy density）. Our calculations show that the accurately calculated transition redshift varies from zT =0.29-0.06^＋0.07 to zT =0.60-0.08^＋0.06 across these models. We also calculate the minimum redshift zc at which the current observations need the universe to accelerate.

关键词： cosmology observations -- distance scale -- supernovae general

Robust Visual Tracking Based on Convolutional Features with Illumination and Occlusion Handing

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Journal of Computer Science & Technology 2018年第1期33卷 223-236页

作者： Kang Li fa-Zhi He Hai-Ping Yu State Key Laboratory of Software Engineering Wuhan University Wuhan 430072 China School of Computer Science Wuhan University Wuhan 430072 China School of Computer Science and Information Engineering Hubei University Wuhan 430062 China

Visual tracking is an important area in computer vision. How to deal with illumination and occlusion problems is a challenging issue. This paper presents a novel and efficient tracking algorithm to handle such problems. On one hand, a target＇s initial appearance always has clear contour, which is light-invariant and robust to illumination change. On the other hand, features play an important role in tracking, among which convolutional features have shown favorable performance. Therefore, we adopt convolved contour features to represent the target appearance. Generally speaking, first-order derivative edge gradient operators are efficient in detecting contours by convolving them with images. Especially, the Prewitt operator is more sensitive to horizontal and vertical edges, while the Sobel operator is more sensitive to diagonal edges. Inherently, Prewitt and Sobel are complementary with each other. Technically speaking, this paper designs two groups of Prewitt and Sobel edge detectors to extract a set of complete convolutional features, which include horizontal, vertical and diagonal edges features. In the first frame, contour features are extracted from the target to construct the initial appearance model. After the analysis of experimental image with these contour features, it can be found that the bright parts often provide more useful information to describe target characteristics. Therefore, we propose a method to compare the similarity between candidate sample and our trained model only using bright pixels, which makes our tracker able to deal with partial occlusion problem. After getting the new target, in order to adapt appearance change, we propose a corresponding online strategy to incrementally update our model. Experiments show that convolutional features extracted by well-integrated Prewitt and Sobel edge detectors can be eff^cient enough to learn robust appearance model. Numerous experimental results on nine challenging sequences show that our proposed

关键词： visual tracking convolutional feature gradient operator online learning particle filter

Controllable synthesis and tunable photocatalytic activity of TiO2 nanowires via alcohol-thermal method

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Rare Metals 2019年第5期38卷 390-396页

作者： Zheng-Xia Xu An-Qi Wang Yong-fa Zhu School of Civil Engineering and Mechanics Yanshan UniversityQinhuangdao 066004China Department of Chemistry Tsinghua UniversityBeijing 100084China

Titania nanowires(TiO2-NW)with tunable aspect ratios and morphologies were directly synthesized using a simple alcohol-thermal ***,ethanol and acetic acid were used as solvents and lithium ion was used as the capping agent to promote the conversion of titanium butoxide into *** morphologies and crystal phases of TiO2-NW were determined by the molar ratio of solvents and the content(mol%)of lithium *** band gap of TiO2-NW with pure anatase phase is slightly bigger than that of TiO2-NW with a mixture of anatase and rutile *** TiO2-NW could achieve effective decolorization of methyl blue(the decolorization rate is over 95%)after 35-min ultraviolet(UV)irradiation.

关键词： Nanowires TiO2 Photocatalysis Degradation Photocurrent