134 research outputs found
Grooming of Dynamic Traffic in WDM Star and Tree Networks Using Genetic Algorithm
The advances in WDM technology lead to the great interest in traffic grooming
problems. As traffic often changes from time to time, the problem of grooming
dynamic traffic is of great practical value. In this paper, we discuss dynamic
grooming of traffic in star and tree networks. A genetic algorithm (GA) based
approach is proposed to support arbitrary dynamic traffic patterns, which
minimizes the number of ADM's and wavelengths. To evaluate the algorithm,
tighter bounds are derived. Computer simulation results show that our algorithm
is efficient in reducing both the numbers of ADM's and wavelengths in tree and
star networks.Comment: 15 page
Properties and application of carbon composite brick for blast furnace hearth
A type of carbon composite brick was produced via the microporous technique
using natural flack graphite, α-Al2O3 and high-quality bauxite chamotte
(Al2O3≥87 mass%) as raw materials with fine silicon powder as additive. The
composition and microstructure of the obtained carbon composite were
characterized using chemical analysis, XRD and SEM with EDS. The high
temperature properties of thermal conductivity, oxidization and corrosion by
molten slag and hot metal of the composite were analyzed. Based on these, the
type of carbon composite brick worked in a blast furnace hearth for six years
was further sampled at different positions. The protective layer was found
and its chemical composition and microscopic morphology were investigated. It
is found that the carbon composite brick combines the good properties of both
the conventional carbon block and ceramic cup refractory. The protective
layer near the hot face consists of two separated sublayers, i.e. the slag
layer and the carbon layer. A certain amount of slag phase is contained in
the carbon layer, which is caused by the reaction of coke ash with the
refractory. No obvious change in the chemical composition of the protective
layer along the depth of the sidewall is found. This work provides a useful
guidance for the extension of the lifetime of blast furnace hearths
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