Correlated colour temperature

Table 1. Chromaticity coordinates (CIE), correlated colour temperature (CCT) and colour rendering indices (CRI) for common white light sources.

The color of a light source is typacally characterized in terms of its color temperature. If the x,y coordinates of an illumination source do not exactly sit on the blackbody locus, the color of a light source is characterized in terms of its CCT. The CCT is the temperature of a blackbody radiator that has a colour that most closely matches the emission from a non-blackbody radiator. For high quality white light illumination the CCT should between 2500K and 6500 K. There is an accepted method (Wyszelki et al 1982) to determine lines of constant correlated color temperature in x, y space. CIE, CCT and CRI for common white light sources are given in Table 1 for comparison purpose (Misra et al 2006). 

Important information was also obtained from kinetic studies on acrylamide formation. When frying potato chips, the acrylamide formation correlates with temperature, its duration and colour of products (Table 12.3). 

History of light and colour measurement A science in the shadows. Taylor Francis, UK Saleh BEA, Teich MC (1991) Fundamentals of photonics. Wiley, New York) See llluminant and Correlated Color Temperature. 

Kinetic observations of the homogeneous part of the reaction in water12,13 do not provide any substantially new element to the knowledge of this system. The obvious observations that the rate of resinification increases with increasing temperature and decreasing pH of the mixture only provide technically useful correlation parameters and the zero-order of reactions carried out to small conversion of 2-furfuryl alcohol13 does not indicate anything except an elementary kinetic approximation (the use of colour build-up as a criterion for the extent of alcohol consumed is also questionable since no firm relationship has ever been established between these two quantities). 

Radial velocities were measured by cross-correlation, using a synthetic spectrum as template. Individual spectra were shifted to rest wavelength and coadded. Effective temperatures were derived from the (V — I)o colours by means of the Alonso calibration [8], We assumed log g = 2.0 for all stars (estimated from isochrones) and with these parameters we fed the spectra to our automatic procedure for the determination of abundances [9], We found that the S/N ratio was too low to be able to determine reliably the microturbulent velocities, the weak Fe I lines could not be measured on many spectra. This resulted in a marked dependence of derived abundances on microturbulent velocities. It is well known that microturbulence is not a truly independent parameter but correlates with surface gravity and, more mildly also with effective temperature. By considering the large sample of stars studied by [10] one can be convinced that for all stars with 1.5 < logg < 3.0 (20 stars) there is no marked dependence from either Tefi or log g, and the mean value of the microturbulent velocity is 1.6 kms 1. For this reason we fixed the microturbulent velocity at 1.6 kms-1. 

Again, there are several choices of extractant, and the preferred one depends mainly on the type of soil under test. One of the most widely used procedures is the Olsen method (Olsen ef al., 1954), which was developed in the USA to correlate crop response to fertilizer on calcareous soils. The amount of P extracted will vary with temperature (increases by 0.43 mg P kg- per degree rise between 20°C and 30°C) and shaking speed, so conditions should be standardized. The extractant is 0.5 M sodium bicarbonate adjusted to pH 8.5. The bicarbonate competes with phosphate on the adsorption sites extracts, and removes most, but not all of it, together with some soluble calcium phosphate. Addition of phosphate-free activated carbon before shaking is necessary if coloured soil extracts are obtained, and then they will require filtration. 

In conclusion, colour changes of medical-grade Y-TZP induced by irradiation with ionising radiation such as y- or X-rays are related to two electron transitions at local lattice defects. The first defect is an intrinsic defect of type Y ZrO that is unstable, in particular at elevated temperatures, and can be correlated with... 

An interesting property of SALAI and its substituted derivatives is their ability to colour markedly under UV irradiation. This photochromism has been attributed to the possible formation of a geometric isomer of the quinoid tautomer. On the other hand, these compounds also exhibit thermochromiSm, which consists of a thermally induced change in colour which increases with an increase of the temperature. This phenomenon has been attributed to intramolecular hydrogen transfer, such as that depicted in Scheme 1. Both processes are reversible and mutually exclusive for the same compound in a given crystalline form. However, since the same anil may exhibit polymorphism, it may be thermochromic in one crystalline form and photochromic in the other. Therefore, these processes should be correlated with differences in the crystal structure rather than with inherent properties of the molecule. All the crystallographic results, which will be reported in Section 20.1.2.3, confirm the earlier hypothesis that molecules which exhibit thermo-chromism are planar, while the others are non-planar, as shown in Figure 1. 

The different effect of titanium catalysts on PET and PBT colour could be related to the thermal degradation. Polycondensation temperature for PET is significantly higher than that of PBT, and titanium(IV) can affect their thermal decomposition in different ways. However, the role of titanium catalysts on PET properties is not elear yet, but, all these problems, the stability, the discoloration, are correlated directly or indirectly to the catalyst composition. 

Bull s Eye solutions (Figure 12.3). The label shows a circular zone filled with diacetylenic monomers that are ready to initiate long polymerisation chains. The process, which is temperature-dependent, allows the chromatic variation of coloured circles to darker tints [10]. This variation is appreciable with or without optical scanners and may be correlated to different sensitivities. In addition, the activation has to be started exactly when foods are packaged. So, Bull s Eye indicators are simply frozen until the final use. Normally, the main targets are fresh and frozen products. 

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