Part One of this essay covers the background, characteristics and drawbacks of functional classification, and evaluates some of the leading alternatives. Part Two continues by proposing a replacement, a sustainable transportation network classification, covering the block-scale and neighborhood-scale relationships.
Optical properties of platinum. Almost all fibers in a fiber optic system must be clad, or coated, in some way. Not only must the light be kept in, but the environment must be kept out to maintain fiber integrity.
Cladding is also used to increase fiber strength. Common optical fibers are clad in a lower index of refraction transparent material. Most cladding is plastic and used at low temperatures.
For a glass fiber this is relatively easy process, since other glasses are available with the same coefficient of thermal expansion and the proper index of refraction. Fiber Coating Process This discussion begins with a description of past research on sapphire fiber cladding, concentrating on work previously performed at TvU .
This discussion is meant to form a background for TvU's work rather than a comprehensive review of all of the work that has been done in the field.
Such a cladding is necessary to prevent light loss if the fiber comes in contact with some light absorbing medium of sufficiently large index of refraction.
The essence of the sapphire fiber cladding problem is that an appropriate transparent cladding material does not exist at first inspection. Glass coatings fail because they have a much lower CTE than sapphire and are subject to chemical attack at high temperatures.
Achieving adhesion to the sapphire is also a major problem; since sapphire is such an inert material it resists chemical bonding. Very reactive materials do bond with sapphire at high temperature, but they also damage the fiber.
Irony in Swift's A Modest Proposal - Although I realize your concern, you have missed the point of this well thought out essay completely. Prof. Paul De Hert's work addresses problems in the area of privacy & technology, human rights and criminal law. To satisfy his multiple curiosities de . Prof. Paul De Hert's work addresses problems in the area of privacy & technology, human rights and criminal law. To satisfy his multiple curiosities de Hert teams up regularly with other authors.
A lack of adhesion during the coating process causes coatings to not cover the fiber completely; gaps appear during processing or use at high temperature.
The development of a high temperature sapphire fiber cladding has been pursued by a number of groups. Transparent sapphire fiber claddings have been attempted in previous research.
USF University of South Florida and researchers in China  have tested a polycrystalline alumina deposition-coated onto sapphire fibers. A smooth, continuous coating was achieved, but was too thin to provide internal reflection at visible wavelengths of light.
USF attempted to use a sol-gel process to coat the fibers. If a sufficiently thick alumina coating could be obtained, it would have a sufficiently different index of refraction from the single crystal sapphire to form an effective cladding.
The USF experiments found that the alumina coating was only 0. The Chinese research had similar problems. Procedures that give a much thicker single coating of alumina also appear impractical.
A different technique was tried at NASA, where a single-crystal alumina fiber was coated with the refractory oxide zirconia.
For this process the fiber was first passed through a slurry of zirconium dioxide particles suspended in the molten vehicle, guanidine 2-ethyl hexanoate.
Incomplete overall coverage was obtained. Another approach to fiber cladding is to add a metal coating to the fiber. The metal cladding on the fiber keeps the light in the fiber by mirror reflection, rather than total internal reflection.
This technique has the weakness that the best metal mirrors have a few percent absorption loss after each reflection, so there will be losses in the fiber as a result of the many bounces of the light passing down the fiber channel.
The target application is relatively short fiber sensors, where some light loss in the fiber is acceptable. Actual losses in a sensor fiber have been shown at TvU to be tolerable as is discussed below.
The phenomenon of the propagation of light down a fiber is a complex interaction of the electromagnetic radiation in the fiber material with a boundary formed by the cladding. Glancing incidence reflection losses can be much lower than normal incidence reflection losses.
A summary of platinum metallizing techniques is given by Baumgartner and Raub : Depending on the deposition process and the parameters involved, the properties of the coating can vary considerably. Those deposited from aqueous electrolytes at thicknesses of a few microns or less are highly stressed and porous, although bright, hard and wear resistant.
Layers produced by the PVD processes are generally in the thickness range of 0. Fired ceramic pastes often form thick layers with internal porosity.
Soaps made from the strong organic base guanidine [ NH2 2C: NH] and organic fatty acids were used as vehicles and binders for coating ceramic fibers with thin precious-metal or metal-oxide films.
This coating was intended to act as a barrier to diffusion in fiber matrix ceramic composite materials. The Pt coating had numerous gaps in the coating over the entire fiber as a result of poor adhesion to the fiber, making this coating process inappropriate for cladding of sapphire fibers.As the table above shows, some African nationalities, particularly Ghanaians and Nigerians, score way above the England mean (and the white British mean), while others, like the Somalis and Congolese, score way below (but still not as low as the Portuguese immigrants, apparently).
|Towards a Functional Classification Replacement (Part Three) | Ped Shed||To satisfy his multiple curiosities de Hert teams up regularly with other authors.|
|Walkable urban design and sustainable places||For a typical small molecule e.|
|Publications||To satisfy his multiple curiosities de Hert teams up regularly with other authors. A human rights approach combined with a concern for theory is the common denominator of all his work.|
My Surnames. COGNOMI ITALIANI "L": © Abstract: The bacterial flagellum is a complex molecular system with multiple components required for functional motility.
Such systems are sometimes proposed as puzzles for evolutionary theory on the assumption that selection would have no function to act on until all components are in place. Measuring The (Nonexistent) Greenhouse Effect in My Backyard with a Handheld IR Thermometer and The Box. Laypersons are no doubt confused by all of our recent esoteric discussions regarding radiative transfer, and whether global warming is even possible from a theoretical standpoint.
Download a print version of this essay.. Part One of this essay covers the background, characteristics and drawbacks of functional classification, and evaluates some of the leading alternatives. Part Two continues by proposing a replacement, a sustainable transportation network classification, covering the block-scale and neighborhood-scale relationships.
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