A token-based routing mechanism for GMPLS-controlled WDM networks

This paper analyzes destination initiated reservation for Generalized Multi-Protocol Label Switching (GMPLS) based wavelength division multiplexing (WDM) networks and determines, via simulation, probabilities of both forward blocking and backward blocking. During light traffic load, any degradation in performance is due to backward blocking, whereas during heavy traffic load forward blocking dominates. In order to minimize performance degradation due to blocking, this paper proposes a token based routing scheme that is capable of searching for the availability of more than one route from source to destination, meeting the desired quality of service (QoS). Extensive simulation results show that the proposed technique significantly improves the blocking performance and setup delay.     

Ordered mesoporous silica fibers: effects of synthesis conditions on fiber morphology and length

Ordered mesoporous silica fibers offer potential industrial application in several areas including polymerization catalysis and separation. Understanding the effects of synthesis conditions on these fibers prepared by the interfacial self-assembly growth method is important to their production and application. The focus of this work is to understand the effect of two previously unstudied factors: silica source height (tetrabutylorthosilicate, TBOS) and the humidity, on the formation of ordered mesoporous silica fibers by the interfacial self-assembly method. Here the TBOS content, interface area, height of source, and humidity of the environment were varied to study their effect on fiber growth. The results show that the TBOS content and interface area do not have a significant impact on results of ordered mesoporous silica fibers. Increasing silica source height or environmental humidity, which lowers the water evaporation rate, gives silica fibers with lower length, less ordered inner pore structure and macroscopic morphology, and smaller pore size. Attempts to mix the growth medium eliminate the fiber morphology and yield gyroidal shapes. A mechanism that combines evaporation of water resulting in local concentration and surfactant, self-assembly, and reaction and diffusion of silica source is proposed to describe the formation of ordered mesoporous silica fibers.     

Dynamic evolution of oxide scale on the surfaces of feed stock particles from cracking and segmenting to peel-off while cold spraying copper powder having a high oxygen content

The oxide scale present on the feedstock particles is critical for inter-particle bond formation in the cold spray(CS)coating process,therefore,oxide scale break-up is a prerequisite for clean metallic contact which greatly improves the quality of inter-particle bonding within the deposited coating.In general,a spray powder which contains a thicker oxide scale on its surface(i.e.,powders having high oxygen content)requires a higher critical particle velocity for coating formation,which also lowers the deposition efficiency(DE)making the whole process a challenging task.In this work,it is reported for the first time that an artificially oxidized copper(Cu)powder containing a high oxygen content of 0.81 wt.%with a thick surface oxide scale of 0.71μm.,can help achieve an astonishing increment in DE.A transition of surficial oxide scale evolution starting with crack initiations followed by segmenting to peeling-off was observed during the high velocity particle impact of the particles,which helps in achieving an astounding increment in DE.Single-particle deposit observations revealed that the thick oxide scale peels off from most of the sprayed powder surfaces during the high-velocity impact,which leaves a clean metallic surface on the deposited particle.This makes the successive particles to bond easily and thus leads to a higher DE.Further,owning to the peeling-off of the oxide scale from the feedstock particles,very few discontinuous oxide scale segments are retained at inter-particle boundaries ensuring a high electrical conductivity within the resulting deposit.Dependency of the oxide scale threshold thickness for peeling-off during the high velocity particle impact was also investigated.