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Michael E. Becker 《Journal of the Society for Information Display》2006,14(11):1003-1017
Abstract— In this paper, methods and instruments for measurement and evaluation of reflection characteristics are reviewed as needed for research and development of electronic displays and for material and surface modeling with ray‐tracing and rendering software packages. Contrast under ambient illumination and recognizability under daylight illumination are prime development targets in the electronic‐display field, while computation and synthesis of realistic scenes and objects are pushing the need for physical data in computer graphics applications. Three categories of instruments are available for detailed reflection analysis. They are based on (1) gonioscopic (mechanical) and conoscopic (optical) directional scanning, (2) imaging approaches, and (3) on arrangements with variable source or receiver aperture. The capabilities, advantages, and limitations of these methods are introduced and discussed in order to facilitate appropriate selection of methods and instruments. For illustration purposes we present typical results obtained from commercial electronic display screens. A basis for continued widespread implementation and standardization of reflection metrology as required for objective rating and comparison of electronic‐display screen performance under ambient illumination is provided. 相似文献
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Wladek T. Sobol L.John SchreinerLjubis̆a Miljković Maria E. Marcondes-HeleneLeonard W. Reeves M.Mik Pintar 《Fuel》1985
The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent. 相似文献
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从理论上研究了纸张背衬不同衬底的光反射率,得出下列表达式:Rb=Ro+(R∞-Ro)×(1/R∞-Ro)/(1/B-Ro)(B为衬底的光反射率),该式简单实用且物理意义明确。利用上述公式,可将Tappi标准列出的Tappi不透明度C0.89的换算公式简化,并可从理论上定性地讨论纸张不透明度与印刷透印性的关系。 相似文献
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Eva M. Valero Juan L. Nieves Sérgio M. C. Nascimento Kinjiro Amano David H. Foster 《Color research and application》2007,32(5):352-360
Many spectral‐recovery methods using RGB digital cameras assume the underlying smoothness of illuminant and reflectance spectra, and apply low‐dimensional linear models. The aim of the present work was to test whether a direct‐mapping method could be used instead of a linear‐models approach to recover spectral radiances and reflectances from natural scenes with an RGB digital camera and colored filters. In computer simulations, a conventional RGB digital camera with up to three colored filters was used to image scenes drawn from a hyperspectral image database. Three measures were used to evaluate recovery with the direct‐mapping method: goodness‐of‐fit, root‐mean‐square error, and a color‐difference metric. It was found that with two and three filters both spectral radiances and reflectances could be recovered sufficiently accurately for many practical applications. With little increase in computational complexity, an RGB camera and a few colored filters can provide significantly better recovery of natural scenes than an RGB camera alone. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 352–360, 2007 相似文献
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李杏娟 《冶金标准化与质量》2003,41(5):45-48
论述了湘钢目前利用煤岩学数据指标判定进厂煤质情况,指导煤场分堆,优化配煤结构.同时在保证焦炭质量稳定的前提下,配入少量低灰的气煤,有效地提高了焦炭质量. 相似文献
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Hussain Sheikha Anil K. Mehrotra Mehran Pooladi-Darvish 《Journal of Petroleum Science and Engineering》2006,53(3-4):189-202
An inverse solution methodology is developed for the estimation of diffusion coefficient of gases in highly viscous, oil-sands bitumens from isothermal, pressure-decay measurements. The approach involves modeling the rate of change in pressure using the diffusion equation for the liquid phase coupled with a mass balance equation for the gas phase. The inverse solution framework is utilized to arrive at two graphical techniques for estimating the diffusion coefficient. Both techniques involve the determination of the slope of a straight line resulting from plotting the experimental data in accordance with the developed model. An advantage of the proposed techniques is that the diffusion coefficient is estimated directly, i.e. without making it an adjustable parameter. The novelty of the proposed method is in its simplicity as well as its ability to isolate portions of the pressure-decay data affected by experimental fluctuations. The effect of the initial pressure on the predicted diffusion coefficient and pressure-decay profile was also investigated. The diffusion coefficients of CO2, CH4, C2H6 and N2 in Athabasca bitumen at 50–90 °C and about 8 MPa were estimated and compared with literature values. 相似文献
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量子阱红外探测器能带结构的计算 总被引:1,自引:1,他引:0
利用电子波在阱与垒的界面上的反射及干涉效应,计算了量子阱红外探测器(QWIP)的能带结构,并对其适用性进行了分析和讨论。通过与K-P模型比较发现,本方法对计算较宽势阱(阱宽大于4nm)的量子阱结构的电子态适合。在垒宽和阱宽不变条件下,用两种方法计算得到的AlGaAs/GaAs量子阱材料中Al组分x与吸收峰值波长λp的关系曲线基本相同。结果说明,在较宽的范围内,本方法对QWIP能带结构的计算是适用且简便的。 相似文献
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