APPLICATION OF CENTRIFUGE MODELS IN THE STUDY OF AN INTERACTION PROBLEM.

Rigid retaining walls are considered. Both the backfill and the soil supporting the foundation of the model wall have been made of a single dry granular soil. Attention is limited to one grain.

Low power all-optical switch in a passive InGaAsP multiple quantum well waveguide

We demonstrate the use of resonant bandfilling nonlinearity in an InGaAsP/InGaAsP Multiple Quantum Well (MQW) waveguide due to photogenerated carriers to obtain switching at pulse powers, which can readily be obtained from an erbium amplified diode laser source. In order to produce gating a polarisation rotation gate was used, which relies on an asymmetry in the nonlinear refraction on the principle axes of the waveguide.

Optimisation of the chirp performance of electroabsorption modulators using a numerical system model

A model to simulate an electroabsorption modulator in a dispersive communications system is described and confirmed experimentally for a 5Gbit/s 100km system. Optimisation of the device shows that transmission of 10Gbit/s over 100km is possible.

A comparison of four sustainable manufacturing strategies

Effective use of materials is one possible component of a sustainable manufacturing strategy. There are many such strategies proposed in the literature and used in practice, with confusion over what they are, what the differences among them may be and how they can be used by practitioners in design and manufacture to improve the sustainability of their product and processes. This paper reviews the literature on sustainable manufacturing strategies that deliver improved material performance. Four primary strategies were found: waste minimisation; material efficiency; resource efficiency; and eco-efficiency. The literature was analysed to determine the key characteristics of these sustainable manufacturing strategies and 17 characteristics were found. The four strategies were then compared and contrasted against all the characteristics. While current literature often uses these strategy titles in a confusing, occasionally inter-changeable manner, this study attempts to create clear separation between them. Definition, scope and practicality of measurement are shown to be key characteristics that impact upon the ability of manufacturing companies to make effective use of the proposed strategy. It is observed that the most actionable strategies may not include all of the dimensions of interest to a manufacturer wishing to become more sustainable, creating a dilemma between ease of implementation and breadth of impact. © 2008 Taylor & Francis.

Fast L0-based sparse signal recovery

This paper develops an algorithm for finding sparse signals from limited observations of a linear system. We assume an adaptive Gaussian model for sparse signals. This model results in a least square problem with an iteratively reweighted L2 penalty that approximates the L0-norm. We propose a fast algorithm to solve the problem within a continuation framework. In our examples, we show that the correct sparsity map and sparsity level are gradually learnt during the iterations even when the number of observations is reduced, or when observation noise is present. In addition, with the help of sophisticated interscale signal models, the algorithm is able to recover signals to a better accuracy and with reduced number of observations than typical L1-norm and reweighted L1 norm methods. ©2010 IEEE.

Direction and polarisation estimation using polarised cylindrical conformal arrays

In this study, the authors describe two-dimensional direction finding and signal polarisation estimation from a cylindrical conformal array consisting of directional and polarised antenna elements. Firstly, a simple and general transformation procedure, based on the mathematical framework of geometric algebra, is presented for arbitrary conformal arrays with polarised and directional antennas. Subsequently, the authors utilise the symmetry of cylindrical arrays to estimate signal parameters via rotational invariance techniques. The authors show how to iteratively estimate the azimuth and elevation angles of the incident signal, as well as its polarisation. To illustrate the versatility of this method, the results of simulations on a 3×4 cylindrical conformal array are shown and discussed. © 2012 The Institution of Engineering and Technology.

The efficiency of compensation grouting in sands

Physical model experiments on compensation grouting in sands were performed in two different setups (Cambridge and Delft). The effect of water-cement (w/c) ratio, bentonite content (b.c.) and injection rate on compensation efficiency was investigated. Results show a considerable drop in compensation efficiency resulted from reducing the soil density. Injection in dense sand (R.D. = 93%) resulted in efficiencies between 40-90%, whereas injection in medium-dense sand (R.D. = 60-75%) yielded in reduced efficiencies between 10-40%. When the w/c ratio increased from 0.5 to 1.5 for a given density (R.D. = 93%) and the b.c. of 4%, the compensation efficiency value decreased. Typical efficiencies were between 60% and 40-50% for w/c ratios of 0.5 and 1.5, respectively. The values of compensation and grout efficiencies were almost equal, suggesting that pressure filtration happens mainly during injection. Increasing the b.c. improved the compensation efficiency. When a higher b.c. of 12% to 14% was used, typical compensation efficiencies in dense sand were 78 and 90% for w/c ratios of 1.5 and 1.8 respectively. © 2012 Taylor & Francis Group.

A systematic approach for improving the quality of official statistics: Case of Korean information and telecommunication industry

With the rapid growth of information and communication technology (ICT) in Korea, there was a need to improve the quality of official ICT statistics. In order to do this, various factors had to be considered, such as the quality of surveying, processing, and output as well as the reputation of the statistical agency. We used PLS estimation to determine how these factors might influence customer satisfaction. Furthermore, through a comparison of associated satisfaction indices, we provided feedback to the responsible statistics agency. It appears that our model can be used as a tool for improving the quality of official ICT statistics. © 2008 Elsevier B.V. All rights reserved.

Some remarks about periodic feedback stabilization

Periodic feedback stabilization is a very natural solution to overcome the topological obstructions which may occur when one tries to asymptotically (locally) stabilize a (locally) controllable nonlinear system around an equilibrium point. The object of this paper is to give a simple geometric interpretation of this fact, to show that one obtains a weakened form of those obstructions when periodic feedback is used, and to illustrate the success of periodic feedback stabilization on a representative system which contains a drift.