40 Gbit/s optical communication system

The University of Bristol is studying the feasibility of deploying 40 Gbit/s optical time division multiplexed (OTDM) transmission networks to support new telecommunication services such the Internet and video-on-demand systems. Among the functional blocks being considered in the project are the optical pulse sources, signal multiplexers and demultiplexers, clock recovery subsystems, signal detection and dispersion accommodation methods.

Feasibility of AlGaInAs lasers for high speed uncooled communication systems

The feasibility of using AlGaInAs lasers for high-speed modulation at high temperatures was evaluated and compared with performance of GaInAsP devices. Both drift-diffusion and rate equation simulation were involved so that the temperature dependence of material parameters was found in terms of overall dynamic performance. Differential gain was estimated by means of drift-diffusion simulations.

Widening engineering horizons: Addressing the complexity of sustainable development

The complex, fragmented and diverse aspects of a sustainable development perspective are translated into an eight-point framework that defines a problem boundary larger than that traditionally adopted by civil engineers. This leads to practical questions intended to inform engineers who ask 'am I being sustainable?' during project implementation. The value of the questions is tested against a case history of a wastewater treatment project. This demonstrates the relevance of the questions to successive project delivery phases of defining the problem, choosing a solution and implementing that solution through design, construction and operation. The case history highlights that answers to several of the additional questions raised by considering this wider problem space are currently buried within government and clients' policies, regulations and standard practice; these answers may not be accessible to the professional engineer.

Optical communication system performance using fibre Bragg grating dispersion compensators

Operating limits of a chirped fibre grating dispersion compensator are determined using a complete optical system model. A 10cm compensator extends the transmission range of an optimised 10Gbit/s MQW electroabsorption modulator from 80km to 425km.

Resonant-cavity LED transceiver arrays for optical wireless communication

155Mb/s operation of an optical wireless link is achieved by using the spectral characteristics and angular emission spectra of a 7-element tracking array of 980nm RC-LEDs. Preliminary results show extension to 200 Mb/s/channel. © 2006 Optical Society of America.

KLAIR: A virtual infant for spoken language acquisition research

Recent research into the acquisition of spoken language has stressed the importance of learning through embodied linguistic interaction with caregivers rather than through passive observation. However the necessity of interaction makes experimental work into the simulation of infant speech acquisition difficult because of the technical complexity of building real-time embodied systems. In this paper we present KLAIR: a software toolkit for building simulations of spoken language acquisition through interactions with a virtual infant. The main part of KLAIR is a sensori-motor server that supplies a client machine learning application with a virtual infant on screen that can see, hear and speak. By encapsulating the real-time complexities of audio and video processing within a server that will run on a modern PC, we hope that KLAIR will encourage and facilitate more experimental research into spoken language acquisition through interaction. Copyright © 2009 ISCA.

Synthesis of positive-real functions with low-complexity series-parallel networks

The purpose of this paper is to continue to develop the recently introduced concept of a regular positive-real function and its application to the classification of low-complexity two-terminal networks. This paper studies five- and six-element series-parallel networks with three reactive elements and presents a complete characterisation and graphical representation of the realisability conditions for these networks. The results are motivated by an approach to passive mechanical control which makes use of the inerter device. ©2009 IEEE.