Aircraft Loss-of-Control: Analysis and Requirements for Future Safety-Critical Systems and Their Validation

Loss of control remains one of the largest contributors to fatal aircraft accidents worldwide. Aircraft loss-of-control accidents are complex, resulting from numerous causal and contributing factors acting alone or more often in combination. Hence, there is no single intervention strategy to prevent these accidents. This paper summarizes recent analysis results in identifying worst-case combinations of loss-of-control accident precursors and their time sequences, a holistic approach to preventing loss-of-control accidents in the future, and key requirements for validating the associated technologies

The Fluorescence Detector of the Pierre Auger Observatory

The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics Research Section

Temperature sensitive controller performance of MR dampers

Magnetorheological (MR) dampers can experience large temperature changes as a result of heating caused by energy dissipation, but control systems are often designed without consideration of this fact. Furthermore, due to the highly nonlinear behavior of MR dampers, many control strategies have been proposed and it is difficult to determine which is the most effective. This paper aims to address these issues through a numerical and experimental study of an MR mass isolator subject to temperature variation. A dynamic temperature dependant model of an MR damper is first developed and validated. Control system experiments are then performed using hardware-in-the-loopsimulations. Proportional, PID, gain scheduling, and on/off control strategies are found to be equally affected by temperature variation. Using simulations incorporating the temperature dependant MR damper model, it is shown that this is largely due to a change in fluid viscosity and the associated movement of the lower clipped optimal' control bound. This zero-volts condition determines how close any controller can perform to the ideal semiactive case, thus all types of controller are affected. In terms of relative performance, proportional and PID controllers perform equally well and outperform the on/off and gain scheduling strategies. Gain scheduling methods are superior to on/off control

NASA Image eXchange (NIX)

This paper discusses the technical aspects of and the project background for the NASA Image exchange (NIX). NIX, which provides a single entry point to search selected image databases at the NASA Centers, is a meta-search engine (i.e., a search engine that communicates with other search engines). It uses these distributed digital image databases to access photographs, animations, and their associated descriptive information (meta-data). NIX is available for use at the following URL: http://nix.nasa.gov./NIX, which was sponsored by NASAs Scientific and Technical Information (STI) Program, currently serves images from seven NASA Centers. Plans are under way to link image databases from three additional NASA Centers. images and their associated meta-data, which are accessible by NIX, reside at the originating Centers, and NIX utilizes a virtual central site that communicates with each of these sites. Incorporated into the virtual central site are several protocols to support searches from a diverse collection of database engines. The searches are performed in parallel to ensure optimization of response times. To augment the search capability, browse functionality with pre-defined categories has been built into NIX, thereby ensuring dissemination of 'best-of-breed' imagery. As a final recourse, NIX offers access to a help desk via an on-line form to help locate images and information either within the scope of NIX or from available external sources

Non-Opportunistic Data Transfer for IoT and Cyber-Physical Systems with Mostly Sleeping Nodes

Sensor networks are frequently used to monitor our environment. From monitoring the habitat of seabirds [1], to the structural integrity of bridges [2]. They can also be used to monitor the arctic tundra to help us monitor climate change. The arctic tundra does however place additional requirements on a monitoring system. Low access to energy sources, human intervention, and networks to transfer the results back, combined with a high likelihood of being destroyed by the environment makes it difficult to successfully retrieve any measurements. The nodes should therefore replicate any measurements among themselves while minimizing the energy consumption. In this thesis, we describe four approaches to schedule connections to share data between a neighborhood of nodes. We also present the implementation of a simulation to evaluate the approaches based on energy usage, broadcast-latency and broadcast-throughput. We conclude that scheduling connections in a ring-like or cluster structure has in general the lowest energy usage at the cost of latency and throughput. However, more work should be done to get a more accurate estimation of the energy usage of the systems

Implementación de un sistema SDN para la movilidad en redes OMNIRAN

This document details all the information needed to understand and test distributed mobility management using the SDN paradigm. This project stars by an analysis of the mobility problem in dense networks. Traditionally mobility has been managed with hierarchical approaches extending the current mobility protocols. But thinking in the future evolution of the network into dense environments some scalability problems appear. The traditional centralized elements may not be able to handle all the traffic in the network and bottlenecks appear at the Mobility Anchors. Nowadays, the problems related to scalability are mostly resolved with hardware upgrades, but in dense environments this couldn’t be enough and surely it would be quite expensive. To find a solution to this problem the IETF has chartered the Distributed Mobility Management (DMM) Group.This project focus on implementing a DMM-based mobility solution designed within the EU FP7 CROWD project. Once the analysis of the problem ended and the requirements of the theoretical solution were defined, we developed all the necessary elements to physically build a distributed network using SDN to manage layer 2 and layer 3.The entities of the network are defined by the CROWD projectin its related publications[9][10]. These districts were run using an SDN implementation called OpenFlow. With all the elements developed we proceed to perform the necessary tests in order to evaluate the distributed mobility management as a solution. This document explains the full design, execution and validationprocesses. Finally all the measurements and statistical data are detailed in order to have an approximation of the services that could achieve the developed network.Ingeniería Telemátic

The avoiding late diagnosis of ovarian cancer (ALDO) project; A pilot national surveillance programme for women with pathogenic germline variants in BRCA1 and BRCA2

Background: Our study aimed to establish â € real-world' performance and cost-effectiveness of ovarian cancer (OC) surveillance in women with pathogenic germline BRCA1/2 variants who defer risk-reducing bilateral salpingo-oophorectomy (RRSO). Methods: Our study recruited 875 female BRCA1/2-heterozygotes at 13 UK centres and via an online media campaign, with 767 undergoing at least one 4-monthly surveillance test with the Risk of Ovarian Cancer Algorithm (ROCA) test. Surveillance performance was calculated with modelling of occult cancers detected at RRSO. The incremental cost-effectiveness ratio (ICER) was calculated using Markov population cohort simulation. Results: Our study identified 8 OCs during 1277 women screen years: 2 occult OCs at RRSO (both stage 1a), and 6 screen-detected; 3 of 6 (50%) were ≤stage 3a and 5 of 6 (83%) were completely surgically cytoreduced. Modelled sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for OC were 87.5% (95% CI, 47.3 to 99.7), 99.9% (99.9-100), 75% (34.9-96.8) and 99.9% (99.9-100), respectively. The predicted number of quality-Adjusted life years (QALY) gained by surveillance was 0.179 with an ICER cost-saving of-£102,496/QALY. Conclusion: OC surveillance for women deferring RRSO in a â € real-world' setting is feasible and demonstrates similar performance to research trials; it down-stages OC, leading to a high complete cytoreduction rate and is cost-saving in the UK National Health Service (NHS) setting. While RRSO remains recommended management, ROCA-based surveillance may be considered for female BRCA-heterozygotes who are deferring such surgery

Electronics in the on-line control of railway movements: quantitative aspects

The present thesis is concerned with a quantitative examination of the on-line control of railway movements and develops a mathematical technique for the evaluation of safety based on the use of Markov processes, illustrated with examples. In addition, the thesis presents a design methodology applicable to electronic safety systems. These systems are shown to be an essential element in the development of fully electronic railway signalling systems, as well as in the increased automation of railway movements. An analysis of the limits of automation of railway movements is described and discussed together with a possible system configuration for the achievement of crewless train operation. The research described herein has been carried out at the British Railways R & D division and the methods described have been successfully applied to real engineering problems. The industrial R & D background of the present thesis is also reflected in the inclusion of a section on the socio-economic consequences of major innovation, particularly in the field of automation and in the consideration of costs and benefits. Section 2 contains an approach evolved jointly with Mr. W.T. Parkman, also at the R & D Division of British Railways, and has been published as Reference 16. Section 5 is a short description or the work carried out by the group under the direct responsibility of the author at the R & D Division of British Railways