5,227 research outputs found
Synthesis and characterization of ultra violet curable renewable polymer graphite composites
This thesis aims is to evaluate the synthesis and characterization of ultra violet (UV) curable renewable polymer graphite (RPG) composites. Accordingly, the renewable polymeric composites were prepared through a film slip casting method at room temperature wherein graphite particles of various weight loadings were mixed with mass proportion 2:1 of renewable monomer and Methylene Diphenyl Diisocyanate, MDI respectively. The main concerned was given to renewable monomer based vegetable cooking oil produced at the SPEN-AMMC UTHM. The morphology-structural relation of the RPG composites confirmed that the graphite particles contain functional groups such as hydroxyl and carboxylic groups are randomly distributed and attributed to formation of interconnected interface within the polymeric composites. Furthermore, as the graphite particle loading increased, the thermal degradation temperature at three distinct decomposition stages shifted and to some extent, resulting in much higher crystallinity. As expected, the mechanical properties of the composites were also enhanced with the modulus and tensile strength increment up to ~440% and ~100% respectively. Significantly, all of these results correlate with viscoelastic properties in which the composites achieved percolation threshold at RPG20 composites. Moreover, the decreased in optical energy band gap (Eg) which afterwards took the leads to electrical conductivity (σ). Aptly, the composites (RPG20, RPG25 and RPG30) were found to possess favorable electrical conductivity range of 10-5 – 10-4 S/m, while all other samples were deemed to be not conductive due to improper dispersion of graphite particulates. On the contrary, UV curable composites did not show any significant enhancement and graphite particle acted as UV stabilizer in this manner. Therefore, the stability of the conductive renewable polymer graphite composite is suitable to be used in various composites applications
Experimental demonstration of gridless spectrum and time optical switching
An experimental demonstration of gridless spectrum and time switching is presented. We propose and demonstrate a bit-rate and modulation-format independent optical cross-connect architecture, based on gridless spectrum selective switch, 20-ms 3D-MEMS and 10-ns PLZT optical switches, that supports arbitrary spectrum allocation and transparent time multiplexing. The architecture is implemented in a four-node field-fiber-linked testbed to transport continuous RZ and NRZ data channels at 12.5, 42.7 and 170.8 Gb/s, and selectively groom sub-wavelength RZ channels at 42.7 Gb/s. We also showed that the architecture is dynamic and can be reconfigured to meet the routing requirements of the network traffic. Results show error-free operation with an end-to-end power penalty between 0.8 dB and 5 dB for all continuous and sub-wavelength channels
Full duplex 60 GHz millimeter wave transmission over multi-mode fiber
Copyright @ 2010 IEEENew wireless subscribers are signing up at an increasing demand of more capacity for ultra-high data rate transfers at speeds more than 1 Gbps, while the radio spectrum is limited. Millimeter wave communication system offers a unique way to resolve these problems. In this paper, the performance of a full duplex transportation system is reported for 1.5 Km of multi-mode fiber length for a sample 10 Gbit/s pseudo random sequence data, with quadrature amplitude modulation mapping and orthogonal frequency division multiplexing modulation with 60 GHz RF and coherent 1550 nm optical carrier. The analysis and simulation results show that the system's quality of service depends on nonlinearity of electro optical modulator, dispersion and signal attenuation impairment of the multi-mode fiber cable
Synchronization of a WDM Packet-Switched Slotted Ring
In this paper, we present two different strategies of
slot synchronization in wavelength-division-multiplexing (WDM)
packet-switched slotted-ring networks. Emphasis is given to the
architecture behind the WDM Optical Network Demonstrator
over Rings (WONDER) project, which is based on tunable
transmitters and fixed receivers. The WONDER experimental
prototype is currently being developed at the laboratories
of Politecnico di Torino. In the former strategy, a slotsynchronization
signal is transmitted by the master station on a
dedicated control wavelength; in the latter, slave nodes achieve
slot synchronization aligning on data packets that are received
from the master. The performance of both synchronization strategies,
particularly in terms of packet-collision probability, was
evaluated by simulation. The technique based on transmitting a
timing signal on a dedicated control wavelength achieves better
performance, although it is more expensive due to the need for an
additional wavelength. However, the technique based on aligning
data packets that are received from the master, despite attaining
lower timing stability, still deserves further study, particularly
if limiting the number of wavelengths and receivers is a major
requirement. Some experimental results, which were measured on
the WONDER prototype, are also shown. Measurement results,
together with theoretical findings, demonstrate the good synchronization
performance of the prototype
A Full-Duplex Diversity-Assisted Hybrid Analogue/Digitized Radio Over Fibre for Optical/Wireless Integration
A duplex Radio Over Fibre (ROF) ring architecture is proposed taking into account the constraints imposed by the cost of fibre laying and of the optical/electronic components, as well as the spectral efficiency and the duplex link performance. It has been shown that relying on Analogue ROF (AROF) and state-of-the-art Digitized ROF (DROF) architectures for downlink and uplink transmission, respectively, attains a high-integrity duplex performance. A sophisticated amalgam of Optical Carrier Suppression (OCS), Code Division Multiplexing (CDM), optical frequency multiplexing, Optical Carrier Reuse (OCR) and distributed antennas is conceived
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