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Non-uniform B-spline curves with multiple shape parameters

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第10期12卷 800-808页

作者： Juan CAO guo-zhao wang School of Mathematical Sciences Xiamen University Xiamen 361005 China Department of Mathematics Zhejiang University Hangzhou 310027 China

We introduce a kind of shape-adjustable spline curves defined over a non-uniform knot *** curves not only have the many valued properties of the usual non-uniform B-spline curves,but also are shape adjustable under fixed control *** method is based on the degree elevation of B-spline curves,where maximum degrees of freedom are added to a curve parameterized in terms of a non-uniform *** also discuss the geometric effect of the adjustment of shape parameters and propose practical shape modification algorithms,which are indispensable from the user's perspective.

关键词： Non-uniform B-spline Shape parameter Degree elevation

Degree elevation of unified and extended spline curves

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第12期15卷 1098-1105页

作者： Xiao-juan DUAN guo-zhao wang Department of Mathematics Zhejiang University

Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this paper is the degree elevation algorithm of UE-spline curves and its geometric meaning. Our main idea is to elevate the degree of UE-spline curves one knot interval by one knot interval. First, we construct a new class of basis functions, called bi-order UE-spline basis functions which are defined by the integral definition of *** some important properties of bi-order UE-splines are given, especially for the transformation formulae of the basis functions before and after inserting a knot into the knot vector. Finally, we prove that the degree elevation of UE-spline curves can be interpreted as a process of corner cutting on the control polygons, just as in the manner of B-splines. This degree elevation algorithm possesses strong geometric intuition.

关键词： Degree elevation Unified and extended splines(UE-splines) Bi-order UE-splines Corner cutting Geometric explanation

Triangular domain extension of linear Bernstein-like trigonometric polynomial basis

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第5期11卷 356-364页

作者： Wan-qiang SHEN guo-zhao wang Department of Mathematics Zhejiang University Hangzhou 310027 China

In computer aided geometric design(CAGD),the Bernstein-Bézier system for polynomial space including the triangular domain is an important tool for modeling free form *** Bernstein-like bases for other spaces(trigonometric polynomial,hyperbolic polynomial,or blended space) has also been ***,none of them was extended to the triangular *** this paper,we extend the linear trigonometric polynomial basis to the triangular domain and obtain a new Bernstein-like basis,which is linearly independent and satisfies positivity,partition of unity,symmetry,and boundary *** prove some properties of the corresponding surfaces,including differentiation,subdivision,convex hull,and so *** applications are shown.

关键词： Computer aided geometric design(CAGD) Free form modeling Trigonometric polynomial Basis function Bernstein basis Triangular domain

Easy cross parameterization for articulated shapes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第10期10卷 1428-1438页

作者： Jian-wei HU Li-gang LIU guo-zhao wang Institute of Computer Graphics and lmage Processing Department of Mathematics Zhejiang University Hangzhou 310027 China Department of Mathematics Huangshan University Huangshan 245041 China

This paper presents a novel interactive system for establishing compatible meshes for articulated *** two mesh surfaces,our system automatically generates both the global level component correspondence and the local level feature *** can use some sketch-based tools to specify the correspondence in an intuitive and easy *** all the other vertex correspondences could be generated *** cross parameterization preserves both high level and low level features of the *** technique showed in the system benefits various applications in graphics including mesh inter-polation,deformation transfer,and texture transfer.

关键词： Sketch Compatible mesh Vertex correspondence Cross parameterization

Adaptive triangular mesh coarsening with centroidal Voronoi tessellations

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 535-545页

作者： Zhen-yu SHU guo-zhao wang Chen-shi DONG Institute of Computer Graphics and lmage Processing Department of Mathematics Zhejiang University Hangzhou 310027 China Laboratory of Information and Optimization Technologies Ningbo Institute of Technology Zhejiang University Ningbo 315100 China

We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a so-called red-green split. Second, the refined mesh is simplified by a clustering algorithm based on centroidal Voronoi tessellations (CVTs). The accuracy and good quality of the output triangular mesh are achieved by combining adaptive subdivision and the CVTs technique. Test results showed the mesh coarsening scheme to be robust and effective. Examples are shown that validate the method.

关键词： Triangular mesh Mesh coarsening Surface subdivision Centroidal Voronoi tessellations (CVTs)

Paths of algebraic hyperbolic curves

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第6期9卷 816-821页

作者： Ya-juan LI Li-zheng LU guo-zhao wang School of Science Hangzhou Dianzi University Hangzhou 310018 China Department of Mathematics Zhejiang University Hangzhou 310027 China

Cubic algebraic hyperbolic （AH） Bezier curves and AH spline curves are defined with a positive parameter a in the space spanned by {1, t, sinht, cosht}. Modifying the value of a yields a family ofAH Bezier or spline curves with the family parameter α. For a fixed point on the original curve, it will move on a defined curve called ＂path of AH curve＂（AH Bezier and AH spline curves） when a changes. We describe the geometric effects of the paths and give a method to specify a curve passing through a given point.

关键词： Algebraic hyperbolic (AH) Bezier curve AH spline curve Path Shape modification

Reduction of 1-3 mm iron ore by H_2 in a fluidized bed

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 620-625页

作者： Jian-ming Pang Pei-min guo Pei zhao Chao-zhen Cao Ding-guo zhao Duo-gang wang The State Key Laboratory for Advanced Steel Processes and Materials Central Iron and Steel Research Institute Beijing 100081 China

The reduction of 1-3 mm fine powder of iron ore by H2 was conducted in a lab-fabricated kg class high temperature fluidized bed. The results show that the differential pressure in the fluidized bed, which has small fluctuation with time, increases with the increase of gas flowing velocity. The utilization ratio of gas decreases when the reaction lasts longer time indicating that the reaction is faster at the beginning of reduction and becomes slower in the latter process. The higher the reaction temperature is, the higher the utilization ratio of gas is, but the difference of utilization ratio among the different temperatures becomes smaller with time. The utilization ratio of gas and the metallization ratio can reach 9% and 84% respectively at 750℃ for 20 min, which shows the reduction reaction by H2 is very fast. The increase of metallization ratio with gas velocity performs quite good linearity, which shows that a higher velocity of reducing gas can be used to improve the productivity of the reactor when H2 is used as reducing gas. With the increase of charge height, the metallization ratio decreases, but the utilization ratio of gas increases. The reaction temperature can be reduced to 700-750℃ from 800-850℃ when H2 is used as reducing gas.

关键词： hydrogen fluidized bed fine powder iron ore ironmaking reduction reaction

Optimistic Transaction Processing in Deterministic Database

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Journal of Computer Science & Technology 2020年第2期35卷 382-394页

作者： Zhi-Yuan Dong Chu-Zhe Tang Jia-Chen wang zhao-guo wang Hai-Bo Chen Bin-Yu Zang Institute of Parallel and Distributed Systems Shanghai Jiao Tong UniversityShanghai 200240China

Deterministic databases can improve the performance of distributed workload by eliminating the distributed commit protocol and reducing the contention ***,the current deterministic scheme does not consider the performance scalability within a single *** this paper,we describe a scalable deterministic concurrency control,Deterministic and Optimistic Concurrency Control(DOCC),which is able to scale the performance both within a single node and across multiple *** performance improvement comes from enforcing the determinism lazily and avoiding read-only transaction blocking the *** evaluation shows that DOCC achieves 8x performance improvement than the popular deterministic database system,Calvin.

关键词： deterministic database concurrency control scalability

Plasma-exfoliated g-C_(3)N_(4) with oxygen doping: tailoring photocatalytic properties

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 27-39页

作者： Yuxin Li Junxin guo Rui Han zhao wang National Engineering Research Centre of Industry Crystallization Technology School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

Heteroatom doping and defect engineering have been proposed as effective ways to modulate the energy band structure and improve the photocatalytic activity of g-C_(3)N_(4). In this work, ultrathin defective g-C_(3)N_(4) was successfully prepared using cold plasma. Plasma exfoliation reduces the thickness of g-C_(3)N_(4) from 10 nm to 3 nm, while simultaneously introducing a large number of nitrogen defects and oxygen atoms into g-C_(3)N_(4). The amount of doped O was regulated by varying the time and power of the plasma treatment. Due to N vacancies, O atoms formed strong bonds with C atoms, resulting in O doping in g-C_(3)N_(4). The mechanism of plasma treatment involves oxygen etching and gas expansion. Photocatalytic experiments demonstrated that appropriate amount of O doping improved the photocatalytic degradation of rhodamine B compared with pure g-C_(3)N_(4). The introduction of O optimized the energy band structure and photoelectric properties of g-C_(3)N_(4). Active species trapping experiments revealed ·O_(2)^(–) as the main active species during the degradation.

关键词： graphitic carbon nitride cold plasma oxygen doping nitrogen defect visible-light photocatalysis