Evaluation of Extended Weak-Equilibrium Conditions for Fully Developed Rotating Channel Flow

The weak-equilibrium condition, which is the basis in the development of algebraic Reynolds stress models is assessed in the prediction of fully developed turbulent channel flow under the influence of system rotation. The budget of the various terms of the exact transport equation for the anisotropy tensor is evaluated by using a DNS database. Two diffusive transport constraints are evaluated by using the DNS data. The results show that neither of them can hold for the near-wall region. An asymptotic analysis of the near-wall behavior is performed and an alternative form of the diffusive transport constraint is proposed. The analysis shows that the proposed alternative diffusive transport constraint has the potential to improve the predictive ability of the resultant ARSM.     

Color Enhancement in Multispectral Image Using the Karhunen-Loeve Transform

We propose a new method for the color enhancement of multispectral image in the visible wavelength region. The purpose of the proposed method is to explore the weak features contained in a specific wavelength by discounting the major color distribution. Such examination will be valuable in visual inspection applications, for example, a medical examination using color image to find a small spectral change of an abnormal part. In this method, Karhunen-Loeve (KL) transform is applied to multispectral data, and specific wavelength components of only high-order KL coefficients are amplified while low-order coefficients are not changed to retain the major color distribution. In the experiment, this method was applied to multispectral images: a printed test image and a human skin image of a bruised arm were captured by a 16-band multispectral camera. The resultant images were compared with the images obtained by saturation enhancement and that obtained by applying the proposed method to the 3-band image. The method successfully visualized the features, which are almost invisible in natural color images, with less change in background color than saturation enhancement.     

Evidence for zero- and pi-phase order parameters of superconducting Nb/Co tri- and pentalayers from the oscillatory behavior of the transition temperature

The oscillation behavior of the superconducting transition temperature Tc as a function of the ferromagnetic Co layer thickness (dCo) has been examined for Nb/Co superconductor(S)/ferromagnetic(F) trilayer series (F/S/F) and pentalayer series (F/S/F/S/F). Tc of the pentalayer series takes a local maximum between dCo=2.0-3.2 nm, where Tc of the trilayer shows a local minimum. This difference in the Tc versus dCo curves provides a clear evidence for the occurrence of the pi phase in the pentalayers, which has been theoretically predicted by Buzdin et al., Radovic et al., and Tagirov.     

Comparative Evaluation of Spectral Transforms for Multispectral Image Coding in Terms of Color Degradation

Recently, multispectral images have been utilized for high fidelity color reproduction through visual telecommunication systems and its compression schemes have been required. However multispectral image coding considering color degradation has not been established. This article presents a comparison of four spectral transforms presented before to find out which transform is more suitable to a spectral decorrelation scheme in transform coding of multispectral images. Transforms dealt with in this paper are Karhunen-Loeve transform (KLT), weighted KLT (WKLT), one mode analysis (OMA) and a transform realizing compatibility to the conventional color systems, latter three of which are designed to represent spectral reflectance functions with small number of coefficients having small colorimetric errors. Through the theoretical and experimental comparisons, it is found that WKLT and OMA reduced colorimetric error compared to the others, where OMA is suitable when the rendering illuminations in the color reproduction can be assumed in advance and WKLT is applicable to other situations.     

Replication technology for optical microsystems

Replication technology is playing an increasingly important role in the production of optical microsystems and micro-optical elements. Hot embossing, injection moulding and UV-embossing all can produce high-quality optical elements in very cost-effective processes. New sol–gel materials allow the combination of replication with lithography to leave selected areas material-free for sawing and bonding. The development of wafer-scale replication technology using UV-curable sol–gel and polymer materials enables refractive and diffractive micro-optical elements as well as micro-mechanical alignment features to be replicated directly onto glass substrates or onto semiconductor device wafers. Grating nanostructures with linewidths less than 100 nm have been replicated into polymer and sol–gel materials for the cost-effective fabrication of large area subwavelength structures for applications such as polarisers and buried grating security features.     

The fluorescence lifetimes of the methyl-substituted benzyl,triphenylmethyl and diphenylmethyl radicals

Time resolved fluorescence of some methyl-substituted benzyl, triphenylmethyl, and diphenylmethyl radicals trapped in rigid solvents at low temperature has been observed. These radicals were excited by pulsed N₂ laser at 337 nm. It is found that these radicals exhibit very long fluorescence lifetime. The long lifetimes of these radicals seem to indicate that the first doublet-doublet electronic transitions of the radicals have a forbidden character.     

Interaction of DNA with hydroxyapatite. Studies on the effect of the phosphate concentration of the column equilibration and washing buffer

The ability of hydroxyapatite to bind DNA effectively in phosphate solutions used for column equilibration, sample loading and column washing has been examined. It was demonstrated that substantial amounts of DNA (up to 40%) were eluted in the washing buffer when the phosphate concentration in the lysing solution or urea-phosphate used for column equilibration, sample loading and column washing was 0.24 M. A reduction in the phosphate concentration from 0.24 to 0.15 M in urea-phosphate solution led to almost 100% binding, whereas a similar reduction in the lysing solution did not. A modified method for loading and eluting DNA from hydroxyapatite columns is presented.