A preliminary comparison of CIE color differences to textile color acceptability using average observers

Ninety‐six nylon pairs were prepared, including red, yellow, green, and blue standards, each at two lightness levels with CIE94 ΔE units ranging from 0.15 to 4.01. Visual assessments of acceptability were carried out by 21 females. Logistic regression compared visual results to four color‐difference equations, CIELAB, CMC, CIE94, and CIEDE2000. It was found that CMC most closely represented judgments of average observers. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 288–294, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20124     

Psychophysical verification of the accuracy of color and color-difference simulations of surface samples on a CRT display

We describe an experiment to visually quantify the accuracy of the simulation of the color and color-difference of surface samples on a CRT display unit. A gray-scale-anchored, magnitude-estimation experiment was performed to assess the absolute quality of the simulations and a forced-choice, paired-comparisons experiment was performed to assess the relative quality of the simulations. Results indicate that an average color difference for overall simulation accuracy can be under 3.0 CIELAB color-difference units for highcolor-temperature sources, and slightly worse for low-colortemperature sources. All simulations were well under the 6 to 12 unit differences reported for typical color reproduction. Possible reasons for the residual color differences between the current simulations and the theoretical limit are presented.     

Variability in estimation of suprathreshold small color differences

Intraobserver and interobserver variability in perceptual small color difference evaluation are known but are rarely analyzed phenomena. They raise the question if humans are equipped to make reliable and uniform estimates of this kind. Data from two recent well‐controlled studies show that intraobserver and, particularly, interobserver variability are surprisingly large. The use of a gray reference scale in place of a single gray reference pair has a small normative effect on the estimate. A large interobserver variability in the estimated magnitude of chromatic differences compared with achromatic reference pairs remains, with an average ratio between largest and smallest estimate of over 3:1 and ratios for individual observers and sample pairs ranging up to 28:1. No correlation was found between the reliability of judgment and the judged magnitude of difference: highly reliable observer groups are not more consistent. Relative reliability of estimate was found inversely related to magnitude of perceived difference. Consequences of these results for the development of improved color difference formulas are discussed. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 367–374, 2009     

Variation in the decisions of observers regarding the ordering of white samples

The variations in the ordering of white samples by different observers have been investigated. Twenty white samples with low to high CIE whiteness indices were prepared and ranked by 22 amateur observers and the variations in the ordering decisions of the observers were compared. Results show a significant consistency between the assessments of the observers for the white samples with low indices of whiteness. However, a large level of disagreement was found between the observers for the whiter samples. In fact, the range of ranks assigned by viewers for each sample increases with an increase in the whiteness of the specimens. Distributions of the assigned orders for the samples are interpreted by considering the CIE whiteness as well as the tinting indices.     

Development of a comprehensive visual dataset based on a CIE blue color center: Assessment of color difference formulae using various statistical methods

The objectives of this work were to develop a comprehensive visual dataset around one CIE blue color center, NCSU‐B1, and to use the new dataset to test the performance of the major color difference formulae in this region of color space based on various statistical methods. The dataset comprised of 66 dyed polyester fabrics with small color differences ($\Delta E_{{\rm ab}}^* < 5$ ) around a CIE blue color center. The visual difference between each sample and the color center was assessed by 26 observers in three separate sittings using a modified AATCC gray scale and a total of 5148 assessments were obtained. The performance of CIELAB, CIE94, CMC(l:c), BFD(l:c), and CIEDE2000 (K_L:K_C:K_H) color difference formulae based on the blue dataset was evaluated at various K_L (or l) values using PF/3, conventional correlation coefficient (r), Spearman rank correlation coefficient (ρ) and the STRESS function. The optimum range for K_L (or l) was found to be 1–1.3 based on PF/3, 1.4–1.7 based on r, and 1–1.4 based on STRESS, and in these ranges the performances of CIEDE2000, CMC, BFD and CIE94 were not statistically different at the 95% confidence level. At K_L (or l) = 1, the performance of CIEDE2000 was statistically improved compared to CMC, CIE94 and CIELAB. Also, for NCSU‐B1, the difference in the performance of CMC (2:1) from the performance of CMC (1:1) was statistically insignificant at 95% confidence. The same result was obtained when the performance of all the weighted color difference formulae were compared for K_L (or l) 1 versus 2. © 2009 Wiley Periodicals, Inc. Col Res Appl, 2011     

Three-dimensional solubility parameters: simple and effective determination of compatibility regions

Methods for the determination of three-dimensional solubility parameters of basic paint components like solvents, film-forming substances and pigments are briefly reviewed. In particular, the conventional method for determining the compatibility regions is described and a new statistical method of analysing experimental data is proposed. The latter makes it possible to determine simply the three-dimensional solubility parameters. A relevant example is given.     

Abnormal Hue-Angle change of the gemstone tanzanite between CIE illuminants d65 and a in CIELAB color space

The blue-to-purple color appearance change observed in some rare specimens of the gemstone tanzanite between daylight and incandescent light is contrary to the hue-angle change calculated between CIE illuminants D65 and A in CIELAB color space. This abnormal calculated hue-angle change for tanzanite can be corrected by using the spectral sensitivity functions of the three kinds of cone photoreceptors to directly calculate color. This study suggests that the cone spectral sensitivity functions are more fundamental in color calculations than the CIE color-matching functions.     

ICP-MS测定不同地区水样中的金属元素

利用电感耦合等离子体质谱仪(ICP-MS),研究12种不同水样中金属元素种类与含量。水样是来自不同地区的矿泉水,温泉水,河水及饮用水。对采集的水样进行过滤和微波消解后用ICP-MS进行检测,根据《食品安全国家标准饮用天然矿泉水》(GB-8537-2018)^([1]),《地表水环境质量标准》(GB-3838—2002)([1]),《地表水环境质量标准》(GB-3838—2002)^([2]),《海洋石油开发工业含油污水排放标准》(GB-4914—1985)([2]),《海洋石油开发工业含油污水排放标准》(GB-4914—1985)^([3]),《生活饮用水卫生标准》(GB-5749—2006)([3]),《生活饮用水卫生标准》(GB-5749—2006)^([4]),对数据进行对比分析,为所测地区水质管理提供严谨的数据分析。对该方法进行加标回收实验,回收率在92%～109%之间。     

CaAlSiN3:Eu/glass composite film in reflective configuration: A thermally robust and efficient red-emitting color converter with high saturation threshold for high-power high color rendering laser lighting

To achieve high color rendering and proper color temperature, a red color converter is essential for phosphor-converted white lighting devices. CaAlSiN₃:Eu²⁺ (CASN) is a highly suitable red phosphor for white light-emitting diodes. However, it can be hardly used in high-power laser lighting due to poor thermal/chemical performance of the phosphor/silicone resin mixture. A series of all-inorganic CASN-based phosphors (e.g., composite ceramic and phosphor-in-glass) were developed to avoid the use of resin. However, new challenges emerged: none of them showed sufficient luminous efficacy (i.e., >50 lm/W) and adequate saturation-threshold (i.e., >30 W or 10 W/mm²). Here, we report a facile fabrication of CASN/glass composite films using a simple and efficient blade-coating method. Upon 450 nm excitation, the resultant composite film presents a high internal quantum efficiency of ~83%, comparable to that of pristine CASN powder (~90%). When irradiated with a blue laser, the composite film shows a record high luminous efficacy of 82 lm/W. Furthermore, its saturation threshold was investigated in high power and high power density mode, respectively. When measured in high power mode, it shows a high saturation threshold over 29.7 W (1.75 W/mm²), thus achieving a high luminous flux of 1576 lm; when measured in high power density mode, it shows a saturation threshold of ~10.2 W/mm² (1.13 W). With abovementioned excellent properties, the CASN/glass composite film has great potential for use in high-power and high color rendering laser lighting.     

Coexistence in a chemostat: Application of a threshold policy

A well known result in chemostat theory states that two populations of microorganisms which compete for a single limiting nutrient cannot coexist under the condition of a spatially uniform environment and time invariant external influences. In this same setting, altering the dilution rate by means of a threshold policy can revert competitive exclusion to species coexistence in a vicinity of a previously chosen concentration.     

乐心道志:先秦礼乐文化中的髹漆乐器

礼乐文化贯穿于我国古代社会的始终,构成了古代文化的核心。将乐的精神与乐器的艺术功能相结合,造就了音乐的灵魂,相辅相承。人们通过演奏乐器,乐心道志,借以表达、交流人的思想情感。先秦时期出土的髹漆乐器实物主要有琴、瑟、笙、鼓、编钟、磬鼓架等。乐器髹漆,形与声有机结合,使漆艺文化与音乐之声交相辉映,悦人耳目,共同演绎了中国人心灵的乐章。     

Neo-impressionism: The most scientific of all schools of color in art

This is an account of French painting immediately before and after the turn of the twentieth century. Here the scientific revelations of such men as Maxwell and Helmholtz, introduced in France by Ogden N. Rood of the United States, played an important role in color expression.     

Three-dimensional mobile adsorption: evaluation of the density distribution in adsorbed phases

Brunet's three-dimensional model for mobile adsorbed phases has been modified to describe adsorption at submonolayer coverages, where Brunet's original theory fails. Here, use of Rudzinski's equation of state, obtained by summation of the virial expansion to infinity, allows us to consider the problem in terms of a radial distribution function. This distribution function in our approach depends parametrically on the Boyle temperature.In this way density profiles and the corresponding adsorption isotherm are evaluated for the system argon—carbon P33(2700) at 77.5 K. The theoretical density profiles behave correctly over a wide pressure range and the corresponding adsorption isotherm yields a good fit to the experimental data. The main conclusion which can be drawn is that the density distribution normal to the surface plays a more important role than was previously assumed.     

Variability in porous ceramic fracture: Influence of apparent density and critical pores

Gypsum specimen failure under four-point bending is investigated both experimentally and numerically. The analysis accounts for the variation in specimen thickness (in a large range from 10 to 90 mm), in pore volume fraction (related to a variation in elastic and fracture properties) and for the presence of macropores that are likely to trigger failure. Examination of specimen fracture surfaces reveals several isolated macropores near the specimen face loaded under tension. The critical pore size does not depend on the specimen volume. The pore criticity does not only depends on its size but also on its location with respect to the specimen face sollicitated under tension. Both pore volume fraction variations between samples and the presence of critical pores induce failure stress scattering for a given specimen width, which is well reproduced numerically using the coupled criterion.     

Variability in fatty acid composition amongArachis genotypes: A potential source of product improvement

Research on peanut (Arachis hypogeae L.) genotypes has shown a high degree of genetic variability in fatty acid composition. The two major oil fatty acids, oleic and linoleic, range between 36–69% and 14–40%, respectively, and together make up 75–85% of total fatty acids. The very long chain (C₂₀–C₂₄) fatty acids make up 4–9%, palmitic acid 7–13%, and stearic acid 2–5% of total fatty acids. Stability of oil samples as measured by length of autoxidation induction period at 60 C shows variable but statistically significant (P<0.01) correlations with levels of linoleic acid; peanut butter samples show similar patterns of stability. Selection for lower levels of linoleic acid in the development of new varieties of peanuts should results in products with significantly improved shelf life. Some genotypes show consistent differences in oil stability patterns that are not related to oil linoleic acid content. Analysis of entries from 16 wildArachis species collections revealed levels of oil linoleic acid higher than those found inA. hypogaea. One species,A. villosulicarpa, contained 49% linoleic acid and 21% very long chain acids. The range in linoleic acid withinA. hypogaea and availability of suitable techniques for measuring selection progress give scope for product improvement through breeding.     

Molecular fractionation in melt-crystallized polyethylene: 3. Microscopy of solvent-treated samples

Microscopy of melt-crystallized polyethylenes treated with hot p-xylene has revealed information concerning the morphology of the systems, in particular the distribution of the segregated low molecular weight material in the structure. It seems that this material, in accordance with earlier reports, is concentrated in the spherulite boundaries and between main lamellae within the spherulites. The effect of thermal treatment and the structure of the material on this morphological aspect is reported.     

Towards automation of color/weave selection in Jacquard design: Model verification

Jacquard woven fabrics are made from colored yarns and different weaves for designing complex pictorial and other patterning effects. The final visualized color effect is the result of assigning weave designs to different areas of the pattern to be created. The current practice in creating Jacquard woven fabric designs is to produce many samples in a trial‐and‐error attempt to match artwork colors. An ability to simulate accurately the appearance of a design prior to manufacture is highly desirable to reduce trial‐and‐error sample production. No automated accurate digital color methodology is yet available to assist designers in matching the patterned woven fabric to the desired artwork. To achieve this, we developed a geometrical model to predict the color contribution of each yarn on the face of the fabric. The geometrical model combined with a Kubelka‐Munk based color mixing model allowed the prediction of the reflectance properties of the final color for a given design. We compared the predicted and experimental values of the reflectance properties for a range of fabrics using the same geometric model with three separate color mixing models. The geometrical model combined with a log‐based color mixing model produced reasonable agreement between predicted and measured ΔE_ab, with an average ΔE_ab of approximately five. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 225–232, 2009     

Corrosion by chlorides in reinforced concrete: Determination of chloride concentration threshold by impedance spectroscopy

Chloride penetration in reinforced concrete induces depassivation of the steel rebars and initiation of the corrosion process leading to degradation of the structure. The coupling of “low-frequency” impedance response with SEM observations and multielementary analyses emphasized that the strong decrease of the capacitive part is related to the corrosion initiation. This experimentally determined incubation period is used in an electrodiffusion model based on Fick's second law to quantify the chloride concentration threshold responsible for corrosion initiation on the reinforcing steel surface. This work thus allowed quantifying the incubation period and the critical chloride concentration, referred to in Tuutti's diagram [K. Tuutti, Corrosion of steel in concrete, CBI Research Report no. 4.82, Swedish Cement and Concrete Research Institute, Stockholm, Sweden, 1982].