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Boontharika Chuenjitkuntaworn Pitt Supaphol Prasit Pavasant Damrong Damrongsri 《Polymer International》2010,59(2):227-235
Poly(L ‐lactic acid) (PLLA) is one of the most studied synthetic biodegradable polymeric materials as a bone graft substitute. Taking into account the osteoconductive property of hydroxyapatite (HAp), we prepared fibrous matrices of PLLA without and with HAp particles in amounts of 0.25 or 0.50% (w/v, based on the volume of the base 15% w/v PLLA solution in 70:30 v/v dichloromethane/tetrahydrofuran). These fibrous matrices were assessed for their potential as substrates for bone cell culture. The presence of HAp in the composite fibre mats was confirmed using energy dispersive X‐ray spectroscopy mapping. The average diameters of both neat PLLA and PLLA/HAp fibres, as determined using scanning electron microscopy, ranged between 2.3 and 3.5 µm, with the average spacing between adjacent fibres ranging between 5.7 and 8.5 µm. The porosity of these fibrous membranes was high (ca 97–98%). A direct cytotoxicity evaluation with L929 mouse fibroblasts indicated that the neat PLLA fibre mats released no substance at a level that was toxic to the cells. The presence of HAp particles at 0.50% w/v in the PLLA fibrous scaffolds not only promoted the attachment and the proliferation of MC3T3‐E1 mouse pre‐osteoblastic cells, but also increased the expression of osteocalcin mRNA and the extent of mineralization after the cells had been cultured on the scaffolds for 14 and 21 days, respectively. The results obtained suggested that the PLLA/HAp fibre mats could be materials of choice for bone tissue engineering. Copyright © 2009 Society of Chemical Industry 相似文献
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Jeff Erickson Damrong Guoy John M. Sullivan Alper Üngör 《Engineering with Computers》2005,20(4):342-353
We present an algorithm to construct meshes suitable for spacetime discontinuous Galerkin finite-element methods. Our method generalizes and improves the Tent Pitcher algorithm of Üngör and Sheffer. Given an arbitrary simplicially meshed domain X of any dimension and a time interval [0, T], our algorithm builds a simplicial mesh of the spacetime domain X × [0, T], in constant time per element. Our algorithm avoids the limitations of previous methods by carefully adapting the durations of spacetime elements to the local quality and feature size of the underlying space mesh.This work was supported in part by The Center for Process Simulation and Design at the University of Illinois, Urbana-Champaign, under NSF ITR grant DMR-0121695. A preliminary version of this paper was presented at the 11th International Meshing Roundtable [9]. 相似文献
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Masaaki Tsuno Monkol Thungchai Damrong Bhanthumkosol Yasuhide Tonogai Chanchai Jaengsawang Amara Kingkate 《Food microbiology》1984,1(2):123-128
Bacteriological quality of water in Chanthaburi province in Thailand was assessed at monthly intervals throughout one year. Water supplies, public wells, bottling factories, reservoirs for rain water and an ice factory were examined. Plesiomonas shigelloides was detected from water supply samples and from well water. Shigella and Salmonella were detected from the treated water supply. Counts of coliform bacteria were above the limit in some cases. 相似文献
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J. P. Pereira C. A. Duarte D. Guoy X. Jiao 《International journal for numerical methods in engineering》2009,77(5):601-633
A high‐order generalized finite element method (GFEM) for non‐planar three‐dimensional crack surfaces is presented. Discontinuous p‐hierarchical enrichment functions are applied to strongly graded tetrahedral meshes automatically created around crack fronts. The GFEM is able to model a crack arbitrarily located within a finite element (FE) mesh and thus the proposed method allows fully automated fracture analysis using an existing FE discretization without cracks. We also propose a crack surface representation that is independent of the underlying GFEM discretization and controlled only by the physics of the problem. The representation preserves continuity of the crack surface while being able to represent non‐planar, non‐smooth, crack surfaces inside of elements of any size. The proposed representation also provides support for the implementation of accurate, robust, and computationally efficient numerical integration of the weak form over elements cut by the crack surface. Numerical simulations using the proposed GFEM show high convergence rates of extracted stress intensity factors along non‐planar curved crack fronts and the robustness of the method. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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An Experimental Study of Sliver Exudation 总被引:1,自引:0,他引:1
We present results on a two-step improvement of mesh quality in three-dimensional Delaunay triangulations. The first step
refines the triangulation by inserting sinks and eliminates tetrahedra with large circumradius over shortest edge length ratio.
The second step assigns weights to the vertices to eliminate slivers. Our experimental findings provide evidence for the practical
effectiveness of sliver exudation.
ID="A1" Correspondence and offprint requests to: H. Edelsbrunner, Department of Computer Science, Duke University, Box 90129, Durham, NC, USA 相似文献
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提出了一种基于微机电系统(MEMS)惯性传感器组合系统的高精度实时人体行为识别算法。算法选取一个2 s的滑动时间窗作为特征提取窗口,提取惯性传感器组合系统输出的时域特征作为特征参量,采用基于平衡决策树的支持向量机对人体不同行为模式进行分类识别。在实验室自主研发的可穿戴智能终端平台上进行测试,结果表明,在识别时间缩短到2 s/次的条件下,对5种行走类行为模式和5种非行走类行为模式的识别率均可达88%。与现有算法相比,该算法的实时性和精度得到明显提高,且拓展了模式识别的种类。 相似文献
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