Model Transduction for Triangle Meshes

This paper proposes a novel method, called model transduction, to directly transfer pose between different meshes, without the need of building the skeleton configurations for meshes. Different from previous retargetting methods, such as deformation transfer, model transduction does not require a reference source mesh to obtain the source deformation, thus effectively avoids unsatisfying results when the source and target have different reference poses. Moreover, we show other two applications of the model ...     

一种改进的Snake模型图像分割算法

针对Snake模型不能收敛到深凹陷区域的缺点,提出一种Snake模型的改进算法.首先把模型不能收敛到深凹陷区域归结为内部能量产生的收缩不足,在此基础上改变新的力,以调整内部能量;然后在不增加参数个数的前提下给出新的能量表达式.算法的实现采用贪婪算法.结果表明,改进的Snake模型能迅速地收敛到凹陷区域,并减少了结果对初值的依赖,明显优于传统Snake模型.     

质子交换膜燃料电池控制器的设计

介绍了基于嵌入式PIC16F876A-I/SP芯片的质子交换膜燃料电池控制器的软硬件的设计,该控制器很好地改善了燃料电池的输出性能.实验结果表明,设计的质子交换膜燃料电池控制器不仅具有保护反应堆和蓄电池等功能,并可以在多变的环境下保持燃料电池的高度可靠性和稳定性.其性能基本达到预期指标.     

Direct raycasting of unstructured cell-centered data by discontinuity Roe-average computation

In the field of computational fluid dynamics (CFD), the upwind finite volume method (FVM) is widely applied to solve 3D flows with discontinuity phenomena (e.g., shock waves). It produces unstructured data at the center of each cell (cell-centered data) with the flow discontinuity constraint on the inner-face between face-neighboring cells. For visualization, existing approaches with interpolation usually pre-extrapolate cell-centered data into cell-vertexed data (data values given at cell vertices) and only handle cell-vertexed data during actual rendering, which unconsciously depress the rendering accuracy and violate the discontinuity constraint. In this paper, we propose a novel method to visualize cell-centered data directly avoiding extrapolation and keep the discontinuity in the rendering data on the framework of multi-pass raycasting. During resampling, the field is reconstructed using the original cell-centered data value and the cell-gradient estimated by Green–Gauss theorem. To keep the discontinuity, we reconstruct the field at an inner-face resampled point using both the face-adjacencies and get two discontinuous field values. Then the field is obtained by computing Roe-average of the two. The analysis and experiments demonstrate that our approach gains a high-accuracy reconstruction and leads to a high-quality image.     

An MLS-based cartoon deformation

We present an image deformation method driven by skeleton; it is based on MLS deformation algorithm (Schaefer et al. in SIGGRAPH, vol. 25, pp. 533–540, 2006). We improve the MLS deformation by defining a new weight function based on skeleton. Being different from the weight function based on control points, our weight function has benefited from the shape information of undeformed object and keeps deformation local, therefore our method can achieve a realistic effect. In cartoon video, we propose a new method to track the skeleton in the video, to build new origin skeleton and new target skeleton on each frame, and to apply our image deformation method to each frame and maintain spatiotemporal consistency. Results demonstrate that our method is able to decrease the effect of squeeze and use less control points.     

Visual simulation of mixed-motion avalanches with interactions between snow layers

In the field of computer graphics, simulation of fluids, including avalanches, is an important research topic. In this paper, we propose a method to simulate a kind of avalanche, mixed-motion avalanche, which is usually large and travels down the slope fast, often resulting in impressive visual effects. The mixed-motion avalanche consists of snow smokes and liquefied snow which form an upper suspension layer and a lower dense-flow layer, respectively. The mixed-motion avalanche travels down the surface of the snow-covered mountain, which is called accumulated snow layer. We simulate a mixed-motion avalanche taking into account these three snow layers. We simulate the suspension layer using a grid-based approach, the dense-flow and accumulated snow layer using a particle-based approach. An important contribution of our method is an interaction model between these snow layers that enables us to obtain the characteristic motions of avalanches, such as the generation of the snow smoke from the head of the avalanche.     

Application-Driven Compression for Visualizing Large-Scale Time-Varying Data

The authors present an application-driven approach to compressing large-scale time-varying volume data. Their approach identifies a reference feature to partition the data into space-time blocks, which are compressed with various precisions depending on their association to the feature. Runtime decompression is performed with bit-wise texture packing and deferred filtering. This method achieves high compression rates and interactive rendering while preserving fine details surrounding regions of interest. Such an application-driven approach could help computational scientists cope with the large-data problem.     

Provable secure identity based generalized signcryption scheme

According to actual needs, a generalized signcryption scheme can flexibly work as an encryption scheme, a signature scheme or a signcryption scheme. In this paper, firstly, we give a security model for identity based generalized signcryption which is more complete than the existing model. Secondly, we propose an identity based generalized signcryption scheme. Thirdly, we give the security proof of the new scheme in this complete model. Compared with existing identity based generalized signcryption, the new scheme has less implementation complexity. Moreover, the new scheme has comparable computation complexity with the existing normal signcryption schemes.     

Fuzzy data modeling and algebraic operations in XML

XML has been the de‐facto standard of information representation and exchange over the web. As the next generation of the Web language, XML is straightforwardly usable over the Internet. At the same time, the real world is filled with imprecision and uncertainty. However, the existed works fall short in their ability to model imprecise and uncertain data using XML. In this paper, we propose a new fuzzy XML data model based on XML Schema. With the model used, the fuzzy information in XML documents can be represented naturally. Along with the model, an associated algebra is presented formally. We also introduce how to use our algebra to capture queries expressed in XQuery. It shows that this model and algebra can establish a firm foundation for publishing and managing the histories of fuzzy data on the Web. © 2010 Wiley Periodicals, Inc.     

Optimal Error Estimates of the Legendre Tau Method for Second-Order Differential Equations

In this paper, we prove that the Legendre tau method has the optimal rate of convergence in L ²-norm, H ¹-norm and H ²-norm for one-dimensional second-order steady differential equations with three kinds of boundary conditions and in C([0,T];L ²(I))-norm for the corresponding evolution equation with the Dirichlet boundary condition. For the generalized Burgers equation, we develop a Legendre tau-Chebyshev collocation method, which can also be optimally convergent in C([0,T];L ²(I))-norm. Finally, we give some numerical examples.