Accepted Manuscripts

Xu Liangyin, Li Yunpeng, Zhang Sheng and Chen Biao Song
J. Comput. Inf. Sci. Eng   doi: 10.1115/1.4038315
This paper presents the SiPESC.Post, an open general visualization system for large scale finite element computation visualization with over millions of or tens of millions of nodes. Base on the system requirement analysis and the processes of finite element visualization system, a new system architecture is proposed, which introduce the stream/filter architecture to meets the needs of large scale data processing and facilitates software maintenances and function extensions. Considering the extension of all parts of the visualization system, a unified extension mechanism is designed and used, which implements the combination of the factory method pattern and the singleton pattern. According to the analysis of features of FEM model, the paper presents the key rapid display technology, which is integrates the VBO OpenGL and removes the internal elements, therefore the large scale model can be displayed efficiently and the system realizes real time operations. Compared with several commercial finite element software systems, the proposed system demonstrates its superiority in visual efficiency and feasibility for super large scale problems and for software maintenance and reuse.
TOPICS: Visualization, Finite element model, Computer software, Finite element analysis, Maintenance, Computation, Filters, System architecture
Bruno S. Machado, Nilanjan Chakraborty, Mohamed Mamlouk and Prodip K. Das
J. Comput. Inf. Sci. Eng   doi: 10.1115/1.4037942
In this study, a three-dimensional agglomerate model of an anion exchange membrane fuel cell is proposed in order to account the detailed composition of the catalyst layers (CLs). Here, a detailed comparison between the agglomerate and a macro-homogeneous model is provided, elucidating the effects of the first implementation on the overall performance and the individual losses, the effects operating temperature and inlet relative humidity on the cell performance, and the catalyst layer utilisation by the effectiveness factor. The results show that the macro-homogeneous model overestimates the cell performance compared to the agglomerate model due to the resistances associated with the species and ionic transport in the catalyst layers. Consequently the hydration is negatively affected, resulting in a higher ohmic resistance. The activation overpotential is over-predicted by the macro-homogeneous model, as the agglomerate model relates the transportation resistances within the domain with the CL composition. Despite the higher utilisation in the anode CL, the cathode CL utilisation presents significant drop near the membrane-CL interface, due to the higher current density and low oxygen concentration. Additionally, the effects of operating temperature and relative humidity at the flow channel inlet were analysed. Similar to the macro-homogeneous model, the overall cell performance of the agglomerate model is enhanced with increasing operating temperature due to the better electrochemical kinetics. However, as the relative humidity at the inlet is reduced, the overall performance of the cell deteriorates due to the poor hydration of the membrane.
TOPICS: Fuel cells, Membranes, Catalysts, Operating temperature, Current density, Oxygen, Transportation systems, Flow (Dynamics), Anodes, Overvoltage
Soji Yamakawa and Kenji Shimada
J. Comput. Inf. Sci. Eng   doi: 10.1115/1.4037227
This paper presents a new method for extracting feature edges from CAD-generated triangulations. The major advantage of this method is that it tends to extract feature edges along the centroids of the fillets rather than along the edges where fillets are connected to non-fillet surfaces. Typical industrial models include very small-radius fillets between relatively large surfaces. Such narrow fillets are unnecessary details for many types of applications and cause numerous problems in the downstream processes. One solution to the small-radius fillet problem is to divide the fillets along the centroid and then merge each fragment of the fillet with non-fillet surfaces. The proposed method can find such fillet centroids and can substantially reduce the adverse effects of such small-radius fillets. The method takes a triangulated geometry as input and first simplifies the model so that small-radius, or "small," fillets are collapsed into line segments. The simplification is based on the normal errors and therefore is scale-independent. It is particularly effective for a shape that is a mix of small and large features. Then the method creates segmentation in the simplified geometry, which is then transformed back to the original shape while maintaining the segmentation information. The groups of triangles are expanded by applying a region-growing technique to cover all triangles. The feature edges are finally extracted along the boundaries between the groups of triangles.
TOPICS: Computer-aided design, Errors, Geometry, Image segmentation, Shapes

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