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.

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.

An ecodesign model based on industry experience

With the increase in environmental legislation facing many industrial sectors organisations are now looking for ways to improve their environmental performance. To a large extent organisations have tended to concentrate on their operations inside the "factory gates" with little regard to the environmental performance of the products they produce. However, this is now changing and some organisations are beginning to take a close look at their products and their effects on the environment during its use phase as well as during the manufacture and disposal phases. At Cranfield University we have carried out a 3 year survey of US, Central European and UK companies claiming to practice ecodesign has been undertaken. Thirty electrical and electronic manufacturers were studied, some through in-depth observation of design programmes, most through semi-structured interviews. The survey and action research sought to understand the way in which these companies practised ecodesign and how they .had implemented ecodesign. A common pattern emerged from the data which suggests that companies successfully implementing ecodesign have many similar experiences. The resulting ecodesign model is presented and discussed, and the factors critical to successful implementation at various stages are explored. The factors cover a range of topics including design management, motivation, design tools, design phases, communication and the designers perspective.

Improving communication in design: Recommendations from the literature

Communication permeates every aspect of an engineer's work-from clarifying product specifications to shaping social ties. This paper offers an overview of recommendations from literature to improve communication within and among engineering teams. We assume communication problems are often the outcome of underlying factors and that it is fruitful to study and improve these influences. Having been empirically elicited in prior research, 24 factors considered in this paper include, e.g., availability of information about product specifications, roles and responsibilities, and overview of sequence of tasks. To improve these factors in order to enable effective communication, this paper collates more than hundred recommendations from journal articles and textbooks published in the fields of engineering design, management science, sociology, and psychology. Recommendations include, for example, identify priorities through risk and bottleneck analysis, give clear descriptions and role expectations, and employ effective process modeling tools. Contributions of this paper are a list of recommendations for industry practitioners and an effort-benefit evaluation of individual recommendations. Copyright © 2002-2012 The Design Society. All rights reserved.

Active dendrites: Adaptation to spike-based communication

Computational analyses of dendritic computations often assume stationary inputs to neurons, ignoring the pulsatile nature of spike-based communication between neurons and the moment-to-moment fluctuations caused by such spiking inputs. Conversely, circuit computations with spiking neurons are usually formalized without regard to the rich nonlinear nature of dendritic processing. Here we address the computational challenge faced by neurons that compute and represent analogue quantities but communicate with digital spikes, and show that reliable computation of even purely linear functions of inputs can require the interplay of strongly nonlinear subunits within the postsynaptic dendritic tree.Our theory predicts a matching of dendritic nonlinearities and synaptic weight distributions to the joint statistics of presynaptic inputs. This approach suggests normative roles for some puzzling forms of nonlinear dendritic dynamics and plasticity.

Visual pattern recognition models for remote sensing of civil infrastructure

As-built models have been proven useful in many project-related applications, such as progress monitoring and quality control. However, they are not widely produced in most projects because a lot of effort is still necessary to manually convert remote sensing data from photogrammetry or laser scanning to an as-built model. In order to automate the generation of as-built models, the first and fundamental step is to automatically recognize infrastructure-related elements from the remote sensing data. This paper outlines a framework for creating visual pattern recognition models that can automate the recognition of infrastructure-related elements based on their visual features. The framework starts with identifying the visual characteristics of infrastructure element types and numerically representing them using image analysis tools. The derived representations, along with their relative topology, are then used to form element visual pattern recognition (VPR) models. So far, the VPR models of four infrastructure-related elements have been created using the framework. The high recognition performance of these models validates the effectiveness of the framework in recognizing infrastructure-related elements.