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1.
D.R. Santos‐Peñate C.M. Campos‐Rodríguez J.A. Moreno‐Pérez 《International Transactions in Operational Research》2019,26(1):340-363
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included. 相似文献
2.
不同表面预处理对有机电致发光显示器性能的影响 总被引:1,自引:1,他引:0
从生产角度研究了基板表面的预处理工艺对OLED性能的影响,分别用UVOzone、氧Plasma以及两者相结合的方式对基板进行表面处理,并按照生产工艺制作器件,从接触角、方阻以及光电特性等测试结果对各种表面处理的样品进行比较。结果表明以上处理都改善了器件性能,不同程度提高了器件的清洁度、亮度和发光效率,其中UVOzone和氧Plasma结合的方式处理效果最为显著,器件在10V时亮度达到79920cd/m2,比其他两种处理方式亮度提高约25%。 相似文献
3.
The purpose of this work is to characterize the sky relative radiance and luminance distributions from the analysis of sky images acquired using a monochromatic CCD wide angle lens camera. The proposed methodology is based on the reduction of the number of the gray levels from the original image, in order to sharpen the different regions of the sky hemisphere, resulting in low level gray scale maps. In these maps each gray level is related to an intensity level and each pixel is associated to a sky direction. An experimental system that is able to simultaneously supply images from the sky and solar irradiance data was developed using a commercial CCD camera. The sky relative radiance and luminance distributions for different sky conditions were also determined. The resultant maps agree with observations of the main characteristics of sky radiance and luminance distributions. 相似文献
4.
The present article reports the investigation of the effects of surrounding brightness on a visual search for three safety colors: red, orange, and yellow. Images of visual stimuli consisting of an array of colored circles placed on a large visual field (a visual angle of 40°) were displayed on an 80‐in. screen with a DLP projector. Experiment I examined the search efficiency under three levels of background luminance that were equivalent to the three target luminances. The results showed that the search efficiency for the orange target decreased as the number of distractors increased, under each of the background luminance levels, whereas the efficiency scarcely decreased for the red and yellow targets. Although a reduction in background luminance increased the search efficiency for the orange target, it is suggested that the effect of background luminance is smaller than the effect of the target color in search efficiency. Experiment II examined the search efficiency under three conditions of low levels of incident illuminance, which were matched with a linear regression to the luminance of color chips of safety colors measured twilight conditions. The results showed that the search efficiency for the orange target decreased as the number of distractors increased under each of the different illuminance conditions, whereas the efficiency scarcely decreased for red and yellow targets. Furthermore, as illuminance decreased, the search time for the orange target was more greatly impacted than for red or yellow. These results imply that the recognition of orange tends to be influenced by the surrounding brightness. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 400–409, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20152 相似文献
5.
An inversion relationship is clarified between lightness and brightness, and also between chroma and colorfulness under nonuniform illumination with different illuminance levels (high and low) within the same visual field. Brightness (or colorfulness) of object color with low lightness (or chroma) under high illuminance level is perceived higher than that of another object color with high lightness (or chroma) under low illuminance level. Two color images are given for showing the inversion phenomena on brightness–lightness and colorfulness–chroma between object colors under different illuminance levels. These color images are useful for making researchers on color understand the differences in concept between brightness and lightness, and also between colorfulness and chroma. In particular, the concept of colorfulness is important, but difficult to understand. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 372–377, 2007 相似文献
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7.
张青文 《土木建筑与环境工程》1992,14(4)
本文介绍了一种测量天空亮度分布的新方法。这种方法利用视场角为180°的鱼眼镜头照相机和计算机数字图像处理系统,实现了天空亮度分布的瞬时测取和胶片密度的高效率处理。文中论述了胶片灰度与天空亮度的标定转换实验方法。引用了误差理论中的数据处理方法确定出二者间的函数关系。通过对昆明和重庆地区晴和阴天空下大量实测结果的误差处论和分析,得到了其相关系数和标准偏差的频数分布图,由此证明了这种方法的可靠性。 相似文献
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9.
A comparative analysis of such methods of defuzzification of fuzzy numbers as WABL (Weighted Averaging Based on Levels), centroid, and mean of maxima (MOM) is presented in the study. Analytic formulas are presented for calculating the defuzzification values for parametrically represented fuzzy numbers of triangular and trapezoidal form. 相似文献
10.
Ralph W. Pridmore 《Color research and application》2007,32(6):469-476
Chromatic luminance (i.e., luminance of a monochromatic color) is the source of all luminance, since achromatic luminance arises only from mixing colors and their chromatic luminances. The ratio of chromatic luminance to total luminance (i.e., chromatic plus achromatic luminance) is known as colorimetric purity, and its measurement has long been problematic for nonspectral hues. Colorimetric purity (pc) is a luminance metric in contrast to excitation purity, which is a chromaticity‐diagram metric approximating saturation. The CIE definition of pc contains a fallacy. CIE defines maximum (1.0) pc for spectral stimuli as monochromatic (i.e., optimal) stimuli, and as the line between spectrum ends for nonspectrals. However, this line has <0.003 lm/W according to CIE colorimetric data and is therefore effectively invisible. It only represents the limit of theoretically attainable colors, and is of no practical use in color reproduction or color appearance. Required is a locus giving optimal rather than invisible nonspectral stimuli. The problem is partly semantic. CIE wisely adopted the term colorimetric purity, rather than the original spectral luminance purity, to permit an equivalent metric for spectrals and nonspectrals, but the parameter of equivalence was never clear. Since 1 pc denotes optimal aperture‐color stimuli for spectrals, arguably 1 pc should denote optimal stimuli consistently for all stimuli. The problem reduces to calculating optimal aperture‐color stimuli (“optimal” in energy efficiency in color‐matching) for nonspectrals, shown to comprise 442 + 613 nm in all CIE illuminants. This remedy merely requires redefinition of 1 pc for nonspectrals as the line 442–613 nm, and gives meaningful pc values over the hue cycle allowing new research of chromatic luminance relations with color appearance. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 469–476, 2007 相似文献