Traffic Alert and Collision Avoidance System (TCAS): Cockpit Display of Traffic Information (CDTI) investigation. Phase 1: Feasibility study

The possibility of the Threat Alert and Collision Avoidance System (TCAS) traffic sensor and display being used for meaningful Cockpit Display of Traffic Information (CDTI) applications has resulted in the Federal Aviation Administration initiating a project to establish the technical and operational requirements to realize this potential. Phase 1 of the project is presented here. Phase 1 was organized to define specific CDTI applications for the terminal area, to determine what has already been learned about CDTI technology relevant to these applications, and to define the engineering required to supply the remaining TCAS-CDTI technology for capacity benefit realization. The CDTI applications examined have been limited to those appropriate to the final approach and departure phases of flight

Riemann-Langevin Particle Filtering in Track-Before-Detect

Track-before-detect (TBD) is a powerful approach that consists in providing the tracker with sensor measurements directly without pre-detection. Due to the measurement model non-linearities, online state estimation in TBD is most commonly solved via particle filtering. Existing particle filters for TBD do not incorporate measurement information in their proposal distribution. The Langevin Monte Carlo (LMC) is a sampling method whose proposal is able to exploit all available knowledge of the posterior (that is, both prior and measurement information). This letter synthesizes recent advances in LMC-based filtering to describe the Riemann-Langevin particle filter and introduces its novel application to TBD. The benefits of our approach are illustrated in a challenging low-noise scenario.Comment: Minor grammatical update

Coronal properties of planet-bearing stars

Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime, conclusive observational evidence is still missing. We want to establish a sound observational basis to confirm or reject major effects of Star-Planet Interactions (SPI) in stellar X-ray emissions. We therefore conduct a statistical analysis of stellar X-ray activity of all known planet-bearing stars within 30pc distance for dependencies on planetary parameters such as mass and semimajor axis. We find that in our sample, there are no significant correlations of X-ray luminosity or the activity indicator L_X/L_bol with planetary parameters which cannot be explained by selection effects. Coronal SPI seems to be a phenomenon which might only manifest itself as a strong effect for a few individual targets, but not to have a major effect on planet-bearing stars in general.Comment: accepted by A&

An integrated opto-mechanical measurement system for in-process defect measurement on a roll-to-roll process

This paper reports on the recent work carried out to develop and implement a high precision on-line optical measurement system with the aim of providing defect detection and characterisation for ALD coated vapour barrier films produced by a roll-to-roll process. This proof-of-concept system is designed to detect and measure pre-existing defects on the film and define their size, location, form and density. The aim is to be able to detect defects in a thin film Al2O3 layer that are critical to vapour barrier performance, and eventually provide valuable process control information. Such an inspection system must be fast in order to evaluate large areas involved (500 mm width foil) at high magnifications. In addition the flexibility of the foil introduces challenges in terms of dealing with surface deviation away from an ideal plane and vibrations. Our solution is a wavelength scanning interferometer (WSI) combined with two kinematic stages, vertical (for auto-focus) and a traverse stage to provide full coverage of the foil. A porous air-bearing conveyor system is used to hold the foil at a fixed height and improve the flatness of the film relative to the measurement plane. This paper describes the principle and design of the inspection system

Wind enhanced planetary escape: Collisional modifications

The problem of thermal escape is considered in which both the effects of thermospheric winds at the exobase and collisions below the exobase are included in a Monte Carlo calculation. The collisions are included by means of a collisional relaxation layer of a background gas which models the transition region between the exosphere and the thermosphere. The wind effects are considered in the limiting cases of vertical and horizontal flows. Two species are considered: terrestrial hydrogen and terrestrial helium. In the cases of terrestrial hydrogen the escape fluxes were found to be strongly filtered or throttled by collisions at high exospheric temperatures. The model is applied to molecular hydrogen diffusing through a methane relaxation layer under conditions possible on Titan. The results are similar to the case of terrestrial hydrogen with wind enhanced escape being strongly suppressed by collisions. It is concluded that wind enhanced escape is not an important process on Titan

In-situ defect detection systems for R2R flexible PV films

The atomic layer deposition technique (ALD) is used to apply a thin (40-100 nm thick) barrier coating of Al2O3 on polymer substrates for flexible PV cells, to minimise and control the degradation caused by water vapour ingress. However, defects appearing on the film surfaces during the Al2O3 ALD growth have been seen to be highly significant in deterioration of the PV module efficiency and lifespan [1]. In order to improve the process yield and product efficiency, it is desirable to develop an inspection system that can detect transparent barrier film defects in the production line during film processing. Off-line detection of defects in transparent PV barrier films is difficult and time consuming. Consequently, implementing an accurate in-situ defects inspection system in the production environment is even more challenging, since the requirements on positioning, fast measurement, long term stability and robustness against environmental disturbance are demanding. For in-situ R2R defects inspection systems the following conditions need to be satisfied by the inspection tools. Firstly the measurement must be fast and have no physical contact with the inspected film surface. Secondly the measurement system must be robust against the environmental disturbance inspection. Finally the system should have sub-micrometre lateral resolution and nanometre vertical resolution in order to be able to distinguish defects on the film surface. Optical interferometry techniques have the potentially to be used as a solution for such application. However they are extremely sensitive to environmental noise such as mechanical vibration, air turbulence and temperature drift. George [2] reported that a single shot interferometry system “FlexCam” developed by 4D Technology being used currently to detect defects for PV barrier films manufactured by R2R technology. It is robust against environmental disturbances; but it has a limited vertical range, which is restricted by the phase ambiguity of the phase shift interferometry. This vertical measurement range (a few hundreds nanometres) is far less than the normal vertical range of defects (a few micrometres up to a few tens micrometres). It is not possible to detect the majority of defects in the R2R flexible PV barrier films

Sidescan Sonar Image Enchancement Using a Decomposition Based on Orthogonal Functions. Applications with Chebyshev Polynomials

A method is presented to remove from sidescan sonar images of the seafloor, artifacts that are clearly unrelated to the backscattering properties of the seafloor. A spectral analysis performed on a ping by ping basis proved to be well suited to the problem. The technique relies on a decomposition using Chebyshev polynomials. This stochastic method does not require a priori knowledge of deterministic parameters. It deals with the low spatial frequency components of the image whose wavelengths are not very small compared to the swath width. Applications to sidescan sonar images obtained with the SeaMARC LI system are presented

Engaging without over-powering: A case study of a FLOSS project

This is the post-print version of the published chapter. The original publication is available at the link below. Copyright @ 2010 IFIP International Federation for Information Processing.The role of Open Source Software (OSS) in the e-learning business has become more and more fundamental in the last 10 years, as long as corporate and government organizations have developed their educational and training programs based on OSS out-of-the-box tools. This paper qualitatively documents the decision of the largest UK e-learning provider, the Open University, to adopt the Moodle e-learning system, and how it has been successfully deployed in its site after a multi-million investment. A further quantitative study also provides evidence of how a commercial stakeholder has been engaged with, and produced outputs for, the Moodle community. Lessons learned from this experience by the stakeholders include the crucial factors of contributing to the OSS community, and adapting to an evolving technology. It also becomes evident how commercial partners helped this OSS system to achieve the transition from an “average” OSS system to a successful multi-site, collaborative and community-based OSS project

A spectrally-accurate FVTD technique for complicated amplification and reconfigurable filtering EMC devices

The consistent and computationally economical analysis of demanding amplification and filtering structures is introduced in this paper via a new spectrally-precise finite-volume time-domain algorithm. Combining a family of spatial derivative approximators with controllable accuracy in general curvilinear coordinates, the proposed method employs a fully conservative field flux formulation to derive electromagnetic quantities in areas with fine structural details. Moreover, the resulting 3-D operators assign the appropriate weight to each spatial stencil at arbitrary media interfaces, while for periodic components the domain is systematically divided to a number of nonoverlapping subdomains. Numerical results from various real-world configurations verify our technique and reveal its universality