Integrated optics for nulling interferometry in the thermal infrared

Modal filtering is based on the capability of single-mode waveguides to transmit only one complex amplitude function to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible in a nulling interferometer. In the present paper we focus on the progress of Integrated Optics in the thermal infrared [6-20 mu m] range, one of the two candidate technologies for the fabrication of Modal Filters, together with fiber optics. In conclusion of the European Space Agency's (ESA) "Integrated Optics for Darwin" activity, etched layers of clialcogenide material deposited on chalcogenide glass substrates was selected among four candidates as the technology with the best potential to simultaneously meet the filtering efficiency, absolute and spectral transmission, and beam coupling requirements. ESA's new "Integrated Optics" activity started at mid-2007 with the purpose of improving the technology until compliant prototypes can be manufactured and validated, expectedly by the end of 2009. The present paper aims at introducing the project and the components requirements and functions. The selected materials and preliminary designs, as well as the experimental validation logic and test benches are presented. More details are provided on the progress of the main technology: vacuum deposition in the co-evaporation mode and subsequent etching of chalcogenide layers. In addition., preliminary investigations of an alternative technology based on burying a chalcogenide optical fiber core into a chalcogenide substrate are presented. Specific developments of anti-reflective solutions designed for the mitigation of Fresnel losses at the input and output surface of the components are also introduced.

Proceedings of the 6th international conference on disability, virtual reality and associated technologies (ICDVRAT 2006)

The proceedings of the conference

Proceedings of the 5th international conference on disability, virtual reality and associated technologies (ICDVRAT 2004)

The proceedings of the conference

Slogger: a profiling and analysis system based on semantic web technologies

Increasingly, distributed systems are being used to host all manner of applications. While these platforms provide a relatively cheap and effective means of executing applications, so far there has been little work in developing tools and utilities that can help application developers understand problems with the supporting software, or the executing applications. To fully understand why an application executing on a distributed system is not behaving as would be expected it is important that not only the application, but also the underlying middleware, and the operating system are analysed too, otherwise issues could be missed and certainly overall performance profiling and fault diagnoses would be harder to understand. We believe that one approach to profiling and the analysis of distributed systems and the associated applications is via the plethora of log files generated at runtime. In this paper we report on a system (Slogger), that utilises various emerging Semantic Web technologies to gather the heterogeneous log files generated by the various layers in a distributed system and unify them in common data store. Once unified, the log data can be queried and visualised in order to highlight potential problems or issues that may be occurring in the supporting software or the application itself.

Special Issue on Virtual Reality Technologies for Disability and Rehabilitation

The papers presented in this issue provide a glimpse of the International Conference on Disability, Virtual Reality and Associated Technologies (ICDVRAT) research community, illustrating advances in virtual reality and associated technologies facilitating interaction in physical and digital environments for individuals and practitioners in disability and rehabilitation. We hope that you will find this issue of interest and recommend this journal and use it to communicate this research to a broader public.

A decade of research and development in disability, virtual reality and associated technologies: review of ICDVRAT 1996−2006

The International Conference (series) on Disability, Virtual Reality and Associated Technologies (ICDVRAT) this year held its sixth biennial conference, celebrating ten years of research and development in this field. A total of 220 papers have been presented at the first six conferences, addressing potential, development, exploration and examination of how these technologies can be applied in disabilities research and practice. The research community is broad and multi-disciplined, comprising a variety of scientific and medical researchers, rehabilitation therapists, educators and practitioners. Likewise, technologies, their applications and target user populations are also broad, ranging from sensors positioned on real world objects to fully immersive interactive simulated environments. A common factor is the desire to identify what the technologies have to offer and how they can provide added value to existing methods of assessment, rehabilitation and support for individuals with disabilities. This paper presents a brief review of the first decade of research and development in the ICDVRAT community, defining technologies, applications and target user populations served.

Input constraints handling in an MPC/feedback linearization scheme

The combination of model predictive control based on linear models (MPC) with feedback linearization (FL) has attracted interest for a number of years, giving rise to MPC+FL control schemes. An important advantage of such schemes is that feedback linearizable plants can be controlled with a linear predictive controller with a fixed model. Handling input constraints within such schemes is difficult since simple bound contraints on the input become state dependent because of the nonlinear transformation introduced by feedback linearization. This paper introduces a technique for handling input constraints within a real time MPC/FL scheme, where the plant model employed is a class of dynamic neural networks. The technique is based on a simple affine transformation of the feasible area. A simulated case study is presented to illustrate the use and benefits of the technique.