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纹理物体表面反射参数的恢复 被引量:3
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作者 孙其民 吴恩华 《计算机研究与发展》 EI CSCD 北大核心 2002年第11期1412-1417,共6页
物体表面反射参数的恢复是新兴的逆向绘制技术中的核心问题 .提出一种恢复物体表面 BRDF模型参数的方法 .假定物体表面的 BRDF模型可以近似分解为漫射纹理和整体不变的镜面反射分量 ,则每一点的反射参数可以用 Phong模型来近似计算 .首... 物体表面反射参数的恢复是新兴的逆向绘制技术中的核心问题 .提出一种恢复物体表面 BRDF模型参数的方法 .假定物体表面的 BRDF模型可以近似分解为漫射纹理和整体不变的镜面反射分量 ,则每一点的反射参数可以用 Phong模型来近似计算 .首先选取物体表面的一片区域 ,利用该区域在不同视点光照条件下采样的几幅图像 ,计算得到该区域的平均镜面反射分量 ,作为整个物体表面的镜面反射分量 ,然后据此从物体表面各点的采样中分离出漫射分量 ,计算各点的漫反射参数 ,得到近似的 BRDF模型 .实验数据表明算法是有效的 . 展开更多
关键词 纹理物理表面反射参数 双向反射分布函数 逆向绘制 光照模型 真空感图像合成 计算机图形学 参数恢复
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机械密封环端面各向异性分形接触分析 被引量:1
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作者 周刚 李晓钟 +1 位作者 朱维兵 张海洋 《润滑与密封》 CAS CSCD 北大核心 2013年第10期55-59,共5页
在M-B分形接触模型的基础上,建立机械密封环端面各向异性的数学模型。在考虑表面各向异性的情况下,分别利用弹性力学和分形接触模型相关原理求出端面接触载荷和弹塑性接触面积,分析表面纹理参数、端面接触载荷和接触面积三者之间的关系... 在M-B分形接触模型的基础上,建立机械密封环端面各向异性的数学模型。在考虑表面各向异性的情况下,分别利用弹性力学和分形接触模型相关原理求出端面接触载荷和弹塑性接触面积,分析表面纹理参数、端面接触载荷和接触面积三者之间的关系。结果表明:当施加一定的接触载荷时,随着表面纹理参数增大,真实接触面积增大,但增速逐渐变缓,弹塑性接触面积的比值在增大;在表面纹理参数不变时,随着真实接触面积的增加所需的接触载荷增大,但增加速逐渐变缓,弹塑性接触面积的比值随着接触载荷的增大而增大。在粗糙表面各向同性和各向异性两种情况下,接触载荷与接触面积的变化趋势是一致的,但考虑表面各向异性时,能更好地反映出真实粗糙表面各个参数之间的关系。 展开更多
关键词 机械密封 表面纹理参数 接触面积 接触载荷
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Evaluation of surface textures and skid resistance of pervious concrete pavement 被引量:7
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作者 陈瑜 王科进 周文芳 《Journal of Central South University》 SCIE EI CAS 2013年第2期520-527,共8页
Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameter... Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs. 展开更多
关键词 pervious concrete surface texture skid resistance fractal dimension ABRASION
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Morphological parameters of both surfaces of coupled joint 被引量:1
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作者 范祥 曹平 +1 位作者 黄雪姣 陈瑜 《Journal of Central South University》 SCIE EI CAS 2013年第3期776-785,共10页
Twenty one joints were made with Brazilian tests and each surface was scanned by the Talysurf CLI 2000. Morphological characteristics of joint surface were quantified by statistical and textural parameters. By the con... Twenty one joints were made with Brazilian tests and each surface was scanned by the Talysurf CLI 2000. Morphological characteristics of joint surface were quantified by statistical and textural parameters. By the contrast of these parameters between both sides of each coupled joint, the following conclusions are drawn. The upper and lower surfaces of coupled joints have approximately equal values of Sp(maximum height of joint surface), Sa(arithmetic mean height of joint surface) and Sq(root mean square height of joint surface), but the Ssk(skewness of the height distribution of joint surface) values of the two surfaces of a coupled joint are different, one is positive while the other is negative. The Saj(auto-correlation length) parameter values of both surfaces of each coupled joint are quite close, and the S^(texture aspect ratio) values have the same situation to the Sal parameter, but the same parameters of different surfaces have big differences which illustrates its own characteristics of each joint. The two surfaces of each coupled joint have similar values of θp (mean profile angle) which can be used to deduce the value of θp each other. 展开更多
关键词 coupled joint morphology statistical parameter textural parameter profile mean angle envelop area
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