Uniqueness of positive solutions for boundary value problems associated with indefinite \u3c6-Laplacian-type equations

This paper provides a uniqueness result for positive solutions of the Neumann and periodic boundary value problems associated with the \u3c6-Laplacian equation 'Equation Presented', where \u3c6 is a homeomorphism with \u3c6(0) = 0, a(t) is a stepwise indefinite weight and g(u) is a continuous function. When dealing with the p-Laplacian differential operator \u3c6(s) = |s|p-2s with p > 1, and the nonlinear term g(u) = u\u3b3 with \u3b3 08 \u211d, we prove the existence of a unique positive solution when \u3b3 \u3f5 ]- 1e, (1 - 2p)/(p - 1)] 2a ]p - 1, + 1e[

Impact of Illumination Correlated Color Temperature, Background Lightness, and Painting Color Content on Color Appearance and Appreciation of Paintings

© 2019, © 2019 Illuminating Engineering Society. Lighting design for art exhibitions has a significant impact on the enjoyment and understanding of the displayed artworks. In particular, the selection of the light sources and the design of the museum space affect the visitors' visual perceptions of the artworks and their color appearance. This project investigated some of the potential factors—the correlated color temperature (CCT) of the illumination, the overall color content of the painting and the lightness of its background—affecting a painting's color appearance and appreciation in a museum setting. The study involved a survey conducted in the laboratory with both naïve observers and lighting experts. The CCT of the lighting was found to be the main factor affecting the painting's appearance and the observers' overall preference for the lighting arrangements, whereas the overall hue content of the painting and the background lightness had a minor influence. Furthermore, it has been found that the perceived brightness increases along with the CCT. ispartof: LEUKOS vol:16 issue:1 pages:25-44 status: publishe

Study on the suitable lighting design of Beato Angelico’s artworks displayed at the National Museum of San Matteo in Pisa (Italy)

The lighting design of exhibition space has a great impact on visual and colour perception and different lighting arrangements can create very different visual impression of artworks and, if not carefully designed, compromise the enjoyment of the viewers. This study involved the design of a new lighting solution for two of Beato Angelico’s artworks displayed at the National Museum of San Matteo (Pisa, Italy). Multiple test lighting configurations were designed using different LED luminaires and different settings of the luminaires. The test lighting configurations were evaluated by a restricted group of observers through a survey in order to individuate the most suitable solution, able to enhance the two artworks simultaneously and to provide a good visual experience for museum visitors

Existence of positive solutions of a superlinear boundary value problem with indefinite weight

We deal with the existence of positive solutions for a two-point boundary value problem associated with the nonlinear second order equation $u''+a(x)g(u)=0$. The weight $a(x)$ is allowed to change its sign. We assume that the function $g\colon\mathopen{[}0,+\infty\mathclose{[}\to\mathbb{R}$ is continuous, $g(0)=0$ and satisfies suitable growth conditions, so as the case $g(s)=s^{p}$, with $p>1$, is covered. In particular we suppose that $g(s)/s$ is large near infinity, but we do not require that $g(s)$ is non-negative in a neighborhood of zero. Using a topological approach based on the Leray-Schauder degree we obtain a result of existence of at least a positive solution that improves previous existence theorems.Comment: 12 pages, 4 PNG figure

High-rate deposition of microcrystalline silicon in a large-area PECVD reactor and integration in tandem solar cells

We study the high-rate deposition of microcrystalline silicon in a large-area plasma-enhanced chemical-vapor-deposition (PECVD) reactor operated at 40.68 MHz, in the little-explored process conditions of high-pressure and high-silane concentration and depletion. Due to the long gas residence time in this process, the silane gas is efficiently depleted using moderate feed-in power density, thus facilitating up-scaling of the process to large surfaces. As observed in more traditional deposition processes, the deposition rate and performance of device-quality material are limited by the inter-electrode gap of the reactor. We significantly increase the cell performances by reducing this gap. X-ray diffractometry (XRD) and secondary ion mass spectroscopy (SIMS) are used to characterize the microcrystalline material deposited in the modified reactor at a rate of 1 nm/s. Comparison with a microcrystalline process at a low deposition rate demonstrates that the crystallographic orientation of the absorbing layer of the cell and the concentrations of contaminants are strongly correlated and dependent on the process. We use microcrystalline cells with absorber layer grown at a rate of 1 nm/s integrated as bottom cells in amorphous-microcrystalline (micromorph) tandem solar cells using the superstrate configuration. We report an initial efficiency of 10.8% (9.6% stabilized) for a tandem cell with 1.2 cm2 surface. Copyright # 2010 John Wiley & Sons, Ltd