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Performance analysis of 3G-UMTS WDM-RoF links

Almeida C., Lima M., Teixeira A.

Optica Applicata

2010

Vol. 40, nr 4

773--789

In this paper, we analyze the impact of using directly modulated lasers and low cost optical amplifiers to propagate 3G-UMTS radio signals over fiber links. First, we perform a simulation study to identify the main impairments in such systems, and then complement the work with laboratory experiments in order to confirm the results and optimize our low cost radio over fiber system.

Frictorq, accessing fabric friction with a novel fabric surface tester

Lima M., Hes L., Vasconcelos R., Martins J.

Autex Research Journal

2005

Vol. 5, no. 4

194--201

A new method to characterise the coefficient of friction of textile fabrics is proposed. The principle is based on the dry clutch, where an annular shaped flat upper body that is kept still, rubs against a lower flat surface, which rotates around a vertical axis at a constant angular velocity. Friction coefficient between the two contacting surfaces is then proportional to the level of the dragging torque between them, measured by means of a precision reaction torque sensor. Contact pressure is constant, given by the own weight of the upper body. The signal from the torque sensor is digitalised through an electronic interface and fed into a PC where friction coefficient is worked out. Finally, experimental work is reported.