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An improved approach to the efficient construction of and search operations in motion graphs

science china(Information sciences) 2012年第5期55卷 1042-1051页

作者： GAO Yan 1,CHEN ZhiHua 2,CHEN MinGang 3 & SHEN Yang 3 1 Software engineering Institute,East china Normal university,shanghai 200062,china 2 department of computer science and engineering,East china university of science and Technology,shanghai 200237,china 3 department of computer science and engineering,shanghai jiao tong university,shanghai 200240,china Software engineering Institute East China Normal University Shanghai China department of computer science and engineering East China University of Science and Technology Shanghai China department of computer science and engineering Shanghai Jiao Tong University Shanghai China

Motion graphs have been widely used as an effective technique in the synthesis of human *** synthesize well-formed motions,motion graphs require smooth transitions and good ***,the time and costs grow quadratically as the graph size *** this paper,we present a method to set up a hierarchical structure,called a structure *** coarse level of this graph models different motion categories and their transitions,and the fine level mainly captures different motion *** interpolation space method is used to improve the graph connectivity at the fine *** structure guides the establishment of a faster and more realistic graphical *** the building process,this structure also helps with searching the motion graph,by performing a traverse search and placing the findings into a direct look-up table or local search ***,when there is no direct link between the different motions,a navigation map is introduced to conduct an appropriate search path via a series of transition motion *** experimental results indicate that our approach could lower the computation time in construction and searching,while simultaneously providing a richer variety of motion styles.

关键词： motion graph structure table registration curve motion interpolation

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Seamlet carving for shape-aware image resizing

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science china(Information sciences) 2012年第5期55卷 1073-1081页

作者： LIN Xiao 1,2,SHENG Bin 1,MA LiZhuang 1,SHEN Yang 1 & CHEN ZhiHua 3 1 department of computer science and engineering,shanghai jiao tong university,shanghai 200240,china 2 Academy of Information Technology,Luoyang Normal university,Luoyang 471022,china 3 department of computer science and engineering,East china university of science and Technology,shanghai 200237,china department of computer science and engineering Shanghai Jiao Tong University Shanghai China Academy of Information Technology Luoyang Normal University Luoyang China department of computer science and engineering East China University of Science and Technology Shanghai China

In this paper we propose an optimized seam-carving approach for anti-shearing image *** image/video seam-carving strategy only focuses on deleting the pixels along 8-connected seams,which may lead to the obvious information loss during *** the traditional seam-carving methods,our approach can construct a seamlet to handle the discontinuous pixels and further achieve an optimized image resizing results with *** particular,to suppress zigzag artifacts,we introduce the anti-shearing energy into the seamlet generation,which includes two steps:1) the energy map is formalized by using Gabor filtering and the saliency map;2) The energy computation is optimized in Gabor feature space to obtain the resizing results without the connectivity *** experimental results and comparisons show the effectiveness of our method.

关键词： image resizing seamlet carving saliency map

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Tissue P systems with parallel rules on channels

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Progress in Natural science:Materials International 2007年第4期17卷 486-491页

作者： Xu Xian (department of computer science and Technology, shanghai jiao tong university, shanghai 200240, china) department of computer science and Technology Shanghai Jiaotong University Shanghai 200240 China

A new variant of P systems as an improvement of the original design is introduced. The P systems here allow parallelism in rules application on synapses (or links, channels), rendering the systems more efficient. We describe the execution mechanism of our P systems, make analysis on its computation power, and illustrate the running by an example.

关键词： tissue P systems parallel rules.

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A RHEOLOGICAL MODEL FOR POLYMER MELTS WITH INTERNAL STRUCTURE IN FLOW FIELDS

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Chinese Journal of Polymer science 1999年第2期17卷 151-158页

作者： Chi-Xing Zhou department of Polymeric Materials science and engineering, shanghai jiao tong university, shanghai 200240, china 上海交通大学高分子材料科学与工程系上海

Conceptually, an imagined conformation ellipsoid is supposed to represent the shape of a polymer chain for polymer melts in flow fields and to be equivalent to the volume element in a mathematical sense in continuum mechanics. A power law dependence of shear modulus of polymer melts on detC, referred to as envelope volume, is proposed. Based on those assumptions and the non-linear relation of shear modulus, a phenomenological viscoelastic model is derived. The model is tested in simple shear flow, simple elongational flow, oscillatory shear flow, and relaxation process after flow suddenly stopped. The results show that the model works well to predict the change of internal structure and viscoelastic performance of polymer melts in flow fields.

关键词： polymer melts rheological model polymer conformation flow fields

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WATER ENTRY OF A WEDGE BASED ON SPH MODEL WITH AN IMPROVED BOUNDARY TREATMENT

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Journal of Hydrodynamics 2009年第6期21卷 750-757页

作者： GONG Kai LIU Hua WANG Ben-long department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200240 China

The hydrodynamic problem of a two-dimensional wedge entering water is studied based on Smoothed Particle Hydrodynamics （SPH） model. A non-reflection boundary treatment for SPH method is proposed to reduce the reflection of sound waves. The boundary pressure is obtained using an improved coupling boundary treatment approach, which is validated by comparing the simulation results with experimental and analytical results in literature. A series of cases with different initial entering velocities are simulated. The maximum force on the wedge and the corresponding time required to reach it for the different cases of initial entering velocities of the wedge are obained and fitted into formulas against the initial entering velocity of the wedge. The maximum drag coefficients of the wedge for the different cases with Froude number greater than 2 are all near the value of 0.91.

关键词： water entry Smoothed Particle Hydrodynamics (SPH) non-reflection boundary

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Identity based signature scheme based on cubic residues

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science china(Information sciences) 2011年第10期54卷 2001-2012页

作者： XING DongSheng,CAO ZhenFu & DONG XiaoLei department of computer science and engineering,shanghai jiao tong university,shanghai 200240,china department of computer science and engineering Shanghai Jiao Tong University Shanghai China

We propose a novel method to compute a cubic root of a cubic residue in Eisenstein *** applying our method,a new identity based signature scheme is proposed based on cubic *** formally prove that our scheme is secure against existential forgery on the adaptive chosen message and identity attacks assuming the hardness of *** scheme is the first identity based signature scheme based on cubic residues.

关键词： Eisenstein ring identity based signature cubic residue factoring random oracle proven security

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CALCULATION OF ADDED MASS OF A VEHICLE RUNNING WITH CAVITY

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Journal of Hydrodynamics 2010年第3期22卷 312-318页

作者： LI Jie LU Chuan-jing HUANG Xuan department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

A numerical method is developed to obtain the added mass coefficients of a vehicle running with cavity in numerical simulation for the multiphase flow of the vehicle which is imposed an added vibration and analyzing its hydrodynamic loads. The method is verified through the cases of non-cavitating sphere and ellipsoid. The changing rule of the added mass of a sphere during water exit is gained. Then the influence of cavitation on the added mass of a cylinder is studied. The results show that λ 11, λ22, λ26, λ66 all decrease as the cavitation number reduces and the length of the attached cavity increases. There is almost a linear relationship between the cavity length and λ22 .The base cavity has great influence on λ11 its contribution decreases more than 60%, when the cavitation number changes from 0.6 to 0.2.

关键词： added mass cavity carrying forced vibration method

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STRUCTURE EVOLUTION OF POLYMER CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

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Chinese Journal of Polymer science 2006年第1期24卷 1-11页

作者： Hong Zheng Wei Yu Hong-bin Zhang and Chi-xing Zhou department of Polymer Materials science & engineering,shanghai jiao tong university,shanghai 200240,china department of Polymer Materials science & engineering Shanghai Jiao Tong University Shanghai 200240 China

Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions, The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.

关键词： Semi-crystalline Polymer Crystallization High-speed Fiber Spinning Process Conformation Finite Element Method (FEM).

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PROPERTIES OF NATURAL CAVITATION FLOWS AROUND A 2-D WEDGE IN SHALLOW WATER

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Journal of Hydrodynamics 2011年第6期23卷 730-736页

作者： CHEN Xin LU Chuan-jing LI Jie CHEN Ying department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China department of engineering Mechanics and State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200240 China

When a body navigates with cavity in shallow water, both flexible free surface and rigid bottom wall will produce great influences on the cavity shape and hydrodynamic performances, and further affect the motion attitude and stability of the body. In the present work, characteristics of the natural cavitating flow around a 2-D symmetrical wedge in shallow water were investigated and the influences of two type boundaries on the flow pattern were analyzed. The Volume Of Fluid （VOF） multiphase flow method which is suitable for free surface problems was utilized, coupled with a natural cavitation model to deal with the mass-transfer process between liquid and vapor phases. Within the range of the cavitation number for computation （0.07-1.81）, the cavity configurations would be divided into three types, viz., stable type, transition type and wake-vortex type. In this article, the shapes of the free surface and the cavity surface, and the hydrodynamic performance of the wedge were discussed under the conditions of relatively small cavitation number （〈0.256）. The present numerical cavity lengths generally accord with experimental data. When the cavitation number was decreased, the cavity was found to become longer and thicker, and the scope of the deformation of the free surface also gradually extends. The free surface and the upper cavity surface correspond fairly to their shapes. However, the lower side of the cavity surface was rather leveled due to the influence of wall boundary. The lift and drag coefficients of this 2-D wedge basically keep linear relations with the natural cavitation number smaller than 0.157, whereas direct proportion for drag and inverse proportion for lift.

关键词： shallow water natural cavitation boundary effect multiphase flow

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HYDRODYNAMIC STUDY ON A PECTORAL FIN ROWING MODEL OF A FISH

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Journal of Hydrodynamics 2009年第4期21卷 463-472页

作者： HU Wen-tong department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China

Fish pectoral fin movement involves primarily a drag-based and a lift-based mechanisms to produce thrust. A numerical study on a pectoral fin rowing propulsion model based on the drag-based mechanism is presented in this article. The propulsive mechanism of the pectoral fin rowing model is related with the voriticity and pressure in the flow field. The relationship between the thrust and kinematic parameters and the wake-captured problem are analyzed. It is shown that a high thrust is produced in the power stroke, mainly due to the backward translation acceleration, the anticlockwise angular acceleration and the absence of stall in the uniform translation. Moreover, the flow control mechanism and the effect of dynamic flexible deformation are further analyzed. To properly choose controllable factors and adopt an appropriate dynamic deformation can improve the propulsive performance.

关键词： pectoral fin drag-based propulsion propulsion mechanism computational fluid dynamics

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