Advances in Science and Technology Vol. 55

Abstract: This paper presents a new method for sputtering solar selective absorber coatings. Radio frequency magnetron reactive sputtering created stainless steel/stainless steel nitride (SS/SS-N) cermet (ceramic-metal composite) thin films under varied nitrogen gas flow ratios. In this present study, a stainless steel material is used for one-target sputtering to manufacture a solar selective absorber film having good solar absorptance of 0.91 and low thermal emittance of 0.06. This sputtering process shows considerable and stable usefulness due to the anti-oxidation and single target. Optical constants n and k have been determined by spectroscopic ellipsometry for cermet composite in a reactive gas flow from 0 percent to 50 percent. Based on the nitrogen content of the film, we used a different oscillator to analyze the film. When the nitrogen gas flow reaches 10 percent, the sputtered film has a significant transformation from metal to cermet properties. When the nitrogen gas flow goes above 17.5 percent, then the film transforms to a dielectric film which can be an anti-reflection layer. A solar absorptance of 0.92 was accepted as the theoretical prediction of optimal selective solar-absorbing three-layer processes which shows that the experimental results agree well with the theoretical prediction.

Abstract: The concept that the civil engineering infrastructure may be streamlined through the use of Smart technology has been mooted for well over a decade. The thought is particularly appealing for large artifacts such as major buildings and bridges. The infrequent but extremely dramatic catastrophic failures particularly of major bridge structures inevitably reignite the debate. This paper endeavours to present a critique of the Smart Bridge both from a technical and socioeconomic perspective. Whilst the basic sensing technology is undoubtedly available there do remain significant areas for necessary improvement, notably in sensor location and damage identification. Additionally the link between the socioeconomic and political domains and the technologists has only recently attracted serious attention. The conclusion is that the tantalising prospect of the Smart Bridge whilst attractive, continues to need substantial technical development and a more effective interface into the economic and planning communities.

Abstract: Well-ordered organosilicate mesoporous coatings with the 3D-hexagonal symmetry are prepared by the sol-gel technique. These films contain high amounts of hydrophobic methyl groups at the pore surface and do not absorb moisture making possible their use as low-index layers in interferential antireflective devices. Besides, these films also appear as good hosts for photochromic dyes leading to coatings for optical switching devices. Methyl groups and mesoporosity offer optimized environments for photochromic dyes dispersed by multiimpregnation technique.

Abstract: Electrochromic (EC) device technology can be used for modulating the transmittance of visible light and solar radiation in windows in buildings as well as for other see-through applications. This paper emphasizes the great energy savings that can be achieved in the built environment, jointly with improved indoor comfort for the users of the building. Manufacturing aspects are considered with particular focus on potentially low-cost methods possible to implement with roll-to-roll technology. In particular the paper discusses recent work on foil-type devices embodying sputter deposited WO3 and NiO-based films joined by a polymer electrolyte.

Abstract: Over the last few years, optical fiber sensors have seen increased acceptance and widespread use for a variety of applications ranging from structural sensing and health monitoring of composites and structures in civil and aeronautic areas; to pressure and temperature sensors for oil and gas reservoir monitoring to name just a few. Among them Fiber Bragg Grating (FBG) based sensors have become widely known and popular within and out the photonics community and seen a rise in their utilization and commercial growth. Given the capability of FBGs to measure a multitude of parameters such as strain, temperature, pressure, chemical and bio-logical agents and many others coupled with their flexibility of design to be used as single point or multi-point sensing arrays and their relative low cost, make them ideal devices to be adopted for a multitude of different sensing applications and implemented in different fields and industries. This work first focuses on some recent experiences in the use of FBGs for opto-acoustic sensors and railway monitoring and then reviews the advances in the area of FBGs evanescent wave sensors as valuable technological platforms for chemical and biological applications.