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41.
Visual evaluation experiments of color discrimination threshold and suprathreshold color‐difference comparison were carried out using CRT colors based on the psychophysical methods of interleaved staircase and constant stimuli, respectively. A large set of experimental data was generated ranged from threshold to large suprathreshold color difference at the five CIE color centers. The visual data were analyzed in detail for every observer at each visual scale to show the effect of color‐difference magnitude on the observer precision. The chromaticity ellipses from this study were compared with four previous published data, of CRT colors by Cui and Luo, and of surface colors by RIT‐DuPont, Cheung and Rigg, and Guan and Luo, to report the reproducibility of this kind of experiment using CRT colors and the variations between CRT and surface data, respectively. The present threshold data were also compared against the different suprathreshold data to show the effect of color‐difference scales. The visual results were further used to test the three advance color‐difference formulae, CMC, CIE94, and CIEDE2000, together with the basic CIELAB equation. In their original forms or with optimized KL values, the CIEDE2000 outperformed others, followed by CMC, and with the CIELAB and CIE94 the poorest for predicting the combined dataset of all color centers in the present study. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 198–208, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20106 相似文献
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The wettability of the lithium surface by liquid alkali metals Na, K and Rb is investigated for the first time by the sessile drop method in an all-soldered instrument under conditions of a high vacuum. The presence of the temperature threshold of wetting is found in Li–Na and Li–K systems at temperatures of 325°C and 160°C, respectively. A conclusion is drawn that an abrupt decrease in wetting angles in the investigated systems is associated with a marked decrease in the interfacial tension at lithium-lithium, lithium-potassium, and lithium--rubidium interfaces owing to the beginning of a noticeable mutual solubility of the components at relatively high temperatures. 相似文献
46.
A revision algorithm is a learning algorithm that identifies the target concept, starting from an initial concept. Such an algorithm is considered efficient if its complexity (in terms of the resource one is interested in) is polynomial in the syntactic distance between the initial and the target concept, but only polylogarithmic in the number of variables in the universe. We give an efficient revision algorithm in the model of learning with equivalence and membership queries for threshold functions, and some negative results showing, for instance, that threshold functions cannot be revised efficiently from either type of query alone. The algorithms work in a general revision model where both deletion and addition type revision operators are allowed. 相似文献
47.
Y. MURAKAMI K. TAKAHASHI R. KUSUMOTO 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(6):523-531
ABSTRACT The fatigue crack growth behaviour of 0.47% carbon steel was studied under mode II and III loadings. Mode II fatigue crack growth tests were carried out using specially designed double cantilever (DC) type specimens in order to measure the mode II threshold stress intensity factor range, ΔKIIth. The relationship ΔKIIth > ΔKIth caused crack branching from mode II to I after a crack reached the mode II threshold. Torsion fatigue tests on circumferentially cracked specimens were carried out to study the mechanisms of both mode III crack growth and of the formation of the factory‐roof crack surface morphology. A change in microstructure occurred at a crack tip during crack growth in both mode II and mode III shear cracks. It is presumed that the crack growth mechanisms in mode II and in mode III are essentially the same. Detailed fractographic investigation showed that factory‐roofs were formed by crack branching into mode I. Crack branching started from small semi‐elliptical cracks nucleated by shear at the tip of the original circumferential crack. 相似文献
48.
本文论述了我国内螺纹铜管业生产、工艺、产品技术条件、齿型及市场现状 ,提出了内螺纹铜管的研发方向。 相似文献
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Wilhelm Heinrichs 《Journal of scientific computing》1991,6(1):1-19
We introduce a stabilized treatment of spectral methods. The condition number of the spectral systems is highly improved. Elliptic and biharmonic problems are considered. Suitable interpolants in the case of inhomogeneous Dirichlet boundary conditions are presented. For a direct solver the improvements with respect to rounding error propagation are numerically demonstrated. 相似文献
50.
珠江口盆地开平凹陷油气聚集条件分析 总被引:2,自引:0,他引:2
珠江口盆地自新生代以来,曾先后受到不同方向张应力的作用,造成了不同时期构造体系的交叉叠合.中中新世以来构造运动强烈,并具有东强西弱的特点,对油气的运移与聚集产生了重要影响.开平凹陷的剧烈断裂和断陷活动始于始新世,并在同期沉积了巨厚的文昌组.晚渐新世以后,由于断裂活动非常微弱,在成熟的烃源岩与其上地层之间缺乏有效的油源断层,因而自生自储、近距离运移可能是开平凹陷油气聚集的基本特征.在凹陷内部,因重力滑动和欠压实泥岩共同作用所形成的KPll-1构造带可能是该区最具有油气远景的地区. 相似文献