Showing papers by "Saab Automobile AB published in 2008"

Vulnerability of European Rail Traffic Management System to Radiated Intentional EMI

Abstract: In this paper, the vulnerability of the future electrified railway system in Europe from a high-power microwave (HPM) source is investigated. The scenario of in-band disturbances radiated toward a GSM-R antenna and damaging the connected communications system is evaluated for different classes of HPM sources and situations. The minimum realistic distances for the different HPM sources from the antenna to cause permanent damage is shown, and the severity of threat from the different sources is discussed.

An AlGaN/GaN HEMT-Based Microstrip MMIC Process for Advanced Transceiver Design

Abstract: A MMIC process in AlGaN/GaN technology for advanced transceiver design has been developed. The process is based on microstrip technology with a complete model library of passive elements and AlGaN/GaN HEMTs. The transistor technology in this process is suitable for both power and low noise design, demonstrated with a power density of 5 W/mm, and an NFmin of 1.4 dB at X-band. Process stability of subcircuits, complementary to power amplifiers and LNAs, in a transceiver system have been investigated. The results indicate that an all AlGaN/GaN MMIC transceiver is realizable using this technology.

Susceptibility of Civilian GPS Receivers to Electromagnetic Radiation

Abstract: Civilian handheld global positioning system receivers were tested for their susceptibility against radiated electromagnetic disturbances of different characteristics and field levels. This susceptibility data were compared to the existing electromagnetic compatibility (EMC) immunity requirements for electronic devices. Some of the receivers were disrupted by continues waves at in- as well as out-of-band frequencies, at field levels far below the existing EMC requirements. The possible reason for this is discussed. In general, due to the ever-growing use of commercial-off-the-shelf equipment even for critical functions, certificates of conformity to current EMC requirements may be inadequate.

Extracting rules from expert operators to support situation awareness in maritime surveillance

Abstract: In maritime surveillance, supporting operatorspsila situation awareness is a very important issue for enabling the possibility to detect anomalous behaviour We present a user study which conceptualises knowledge to be implemented in a rule-based application aiming at supporting situation awareness Participatory observations were used as a method for extracting operatorspsila knowledge The result of the user study is in the form of a number of identified rules emerging from organisational factors, group thinking and individual experience A description of the rule-based prototype is presented a long with the result from the user study This is also discussed together with the applicability of rule based systems and how to support situation awareness

Increasing ZigBee network lifetime with X-MAC

Abstract: The ZigBee standard builds on the assumption that infrastructure nodes have a constant power supply. ZigBee therefore does not provide any power-saving mechanisms for routing nodes, which limits the lifetime of battery-powered ZigBee networks to a few days. This short lifetime drastically restricts the possible application scenarios for ZigBee. To expand the usefulness of ZigBee, we present a ZigBee implementation where we replace the default ZigBee MAC protocol with the power-saving MAC protocol X-MAC. Our results show that X-MAC reduces the power consumption for ZigBee routing nodes with up to 90%, leading to a ten-fold increase in network lifetime at the price of a slight increase in network latency. Furthermore, we are the first to experimentally quantify the energy-efficiency of X-MAC in a multihop scenario. Our results indicate that X-MAC reduces the power consumption of idle nodes that are within communication range of two communicating nodes, suggesting that X-MAC may be able to mitigate the hot-spot problem in sensor networks.

Finding behavioural anomalies in public areas using video surveillance data

Abstract: In this paper we propose an approach for detecting anomalies in data from visual surveillance sensors. The approach includes creating a structure for representing data, building ldquonormal modelsrdquo by filling the structure with data for the situation at hand, and finally detecting deviations in the data. The approach allows detections based on the incorporation of a priori knowledge about the situation and on data-driven analysis. The main advantages with the approach compared to earlier work is the low computational requirements, iterative update of normal models and a high explainability of found anomalies. The proposed approach is evaluated off-line using real-world data and the results support that the approach could be used to detect anomalies in real-time applications.

Radar level gauge system and coupling

Abstract: A radar level gauge system for measuring a filling level of a content contained in a tank is disclosed. The system comprises a transmitter and a probe, configured to guide transmitted microwave energy towards the content. Further, it comprises a coupling comprising a mechanical connection configured to mechanically connect the probe to the tank; an electric feed-through configured to electrically connect the probe to the transmitter; and a seal adapted to hermetically seal the electric feed- through, wherein the coupling is adapted to provide mechanical separation between said mechanical connection and said seal, and to permit at least some movement between the mechanical connection and the seal, thereby protecting the seal from forces acting on the probe.

Absorber loading study in FOI 36.7 m 3 mode stirred reverberation chamber for pulsed power measurements

Abstract: A feasibility study was conducted to gain better understanding of the influence of different Q-values of a 36.7 m3 reverberation chamber. The chamber was loaded with different types and numbers of microwave absorbers. For different chamber Q-values, the lowest usable frequency for 200 uncorrelated stirrer positions the agreement with the expected exponential power distribution, the chamber time constant and field build up process, has been studied.

On Visual, Vibrotactile, and 3D Audio Directional Cues for Dismounted Soldier Waypoint Navigation:

Abstract: We compared a visual GPS, a tactile torso belt, and a 3D audio display in a waypoint navigation task for dismounted soldiers. Using these displays one at a time, the soldier's main tasks were to wa...

Explicit FE-Formulation of Interphase Elements for Adhesive Joints

Abstract: The potential of adhesive bonding to improve the crashworthiness of cars is attracting the automotive industry. Large-scale simulations are time consuming when using the very small finite elements needed to model adhesive joints using conventional techniques. In the present work, a 2D-interphase element formulation is developed and implemented in an explicit FE-code. A simplified joint serves as a test example to compare the interphase element with a straightforward continuum approach. A comparison shows the time-saving potential of the present formulation as compared to the conventional approach. Moreover, the interphase element formulation shows fast convergence and computer efficiency.

On the response and immunity of electric power infrastructures against IEMI — Current Swedish initiatives

Abstract: IEMI is not a new research topic especially for military applications. However, not much attention has been paid in the past to the possibility that this type of threat could be used against civilian critical infrastructure by terrorist groups or other rough elements. Moreover, just a few research programs, mainly conducted in the U.S., have been reported combining power systems and high altitude nuclear high-altitude electromagnetic (HEMP) pulse. The present manuscript is aimed to present various Swedish research activities planned to provide the necessary knowledge to improve the electromagnetic requirements/susceptibility level against IEMI threats of future digital and electronic components used on different critical infrastructures system.

Extending the scope of situation analysis

Abstract: The use of technology to assist human decision making has been around for quite some time now. In the literature, models of both technological and human aspects of this support can be identified. However, we argue that there is a need for a unified model which synthesizes and extends existing models. In this paper, we give two perspectives on situation analysis: a technological perspective and a human perspective. These two perspectives are merged into a unified situation analysis model for semi-automatic, automatic and manual decision support (SAM)2. The unified model can be applied to decision support systems with any degree of automation. Moreover, an extension of the proposed model is developed which can be used for discussing important concepts such as common operational picture and common situation awareness.

Positioning embedded software maintenance within industrial maintenance

Abstract: Little is known about of how software embedded in complex industrial technical systems is maintained. In this paper, we identify industrial maintenance process steps and position software maintenance activities within them. We do this in the context of JAS 39 Gripen, a multi-role combat aircraft developed by Saab.

Application of CFD modelling for energy efficient humidity management of an electronics enclosure in storage under severe climatic conditions

Abstract: A CFD modelling methodology including experimental validation has been developed and applied for investigation of anti-moisture measures in a non- hermetic electronics enclosure containing a number of printed circuit boards, and placed in a severe storage environment. In the climatic test the temperature and the relative humidity have been varried from +33degC to +71degC and from 14% to 80%, respectively. Enclosure heater solutions have been parametrically studied by simulation. A heating strategy involving various power levels has been determined, which is just sufficient to maintain the internal relative humidity below 60%, thereby reducing the risk for dew formation on the electronics assembly.

A 25m2 Target-Aligned Heliostat with Closed-Loop Control

Abstract: A 25m2 target-aligned research heliostat with closed-loop control, with a theoretical concentration of 80 suns, has been built at CSIR in South Africa. The heliostat has four degrees of freedom: Azimuth, Elevation, Rotation and Pitch. A control system making use of a solar tracker has been developed and tested on a 1.25m2 target-aligned miniheliostat. A tracking accuracy of 3.3 milliradians was obtained. A good focal spot has been obtained with the 25m2 target-aligned research heliostat.

Dedicated measurement campaign for definition of accurate reference pattern of the VAST12 antenna

Abstract: In this paper, three possible approaches for definition of a highly accurate reference pattern of a reference antenna are described and their pros and contras are discussed. Following the most reliable approach, a dedicated measurement campaign was planned and carried out in 2007-2008 for definition of the highly accurate reference pattern of the VAST12 antenna. In planning the campaign, conclusions from the first comparison campaign with the VAST12 carried out within the ACE network in 2004-2005 were taken into account and these are also presented and discussed. Some typical measurement errors and uncertainties are listed and briefly discussed.

Image Retrieval Simulations for the GEO Atmospheric Sounder (GAS)

Abstract: The GEO atmospheric sounder (GAS) is a potential European future instrument, which utilizes interferometric synthetic aperture radiometry to obtain the desired spatial (30 km) and temporal (30 minutes) resolution for measurement of atmospheric temperature and humidity profiles under all weather conditions This paper presents a simulation model for the entire imaging process It enables detailed simulation of the impact of the instrument characteristics on the imaging performance The model has been used as a tool to predict the performance of an instrument demonstrator under development

Estimation of process parameter variations in a pre-defined process window using a Latin hypercube method

Abstract: The aim of this paper is to present a methodology that provides an analytical tool for estimation of robustness and response variation within a pre-defined process window. To exemplify the developed methodology, the stochastic simulation technique is used for a sheet-metal forming application. A sampling plan based on the Latin hypercube sampling method for variation of design parameters is utilized, and the thickness reduction is specified as the response. Moreover, the response surface methodology is applied for understanding the quantitative relationship between design parameters and response value. The conclusions of this study are that the applied method gives a possibility to illustrate and interpret the variation of the response versus a design parameter variation. Consequently, it gives significant insights into the usefulness of individual design parameters. It has been shown that the method enables us to estimate the admissible design parameter variations and to predict the actual safe margin for given process parameters. Furthermore, the dominating design parameters can be predicated using sensitivity analysis, and this in its turn clarifies how the reliability criteria are met. Finally, the developed software can be used as an additional module for set-up of stochastic finite element simulations and to collect the numerical results from different solvers within different applications.

Design of augmented reality for collaboration

Abstract: Augmented Reality has potential to support collaboration in complex situations, such as command and control. Unfortunately there are few studies on how such systems should be designed to facilitate cooperation between actors from different organisations and at the same time support individual actors needs. This poster presents an iterative design process of an Augmented Reality system for a collaborative task.

Prognostics of electronic systems through power supply current trends

Abstract: As today's avionic systems highly rely on electronic components, the prognostic of electronic systems in the context of avionics has become crucial. This paper presents a prognostic method applicable to electronic components and systems based on the analysis of the power supply current. In this method, the focus is on trends in the measured power supply current of the device under prognostic process. The discussion in this paper reveals that there is a measurable relationship between the supply current and the remaining lifetime of the electronic devices. The presented methodology is supported by circuit simulations performed on a system consisting of reference circuitry. The prognostic method shows great promise due to the ability of being applicable at any prognostic level.

Evaluation of Preventive Maintenance Task Intervals Using Field Data from a Complete Life Cycle

Abstract: In this paper the appropriateness of initial preventive maintenance task intervals and the improvement of changed intervals are evaluated. The evaluation criteria are partly derived from logic found in the RCM (Reliability-Centered Maintenance) methodology. Empirical data is related to the whole life cycle of the Swedish military aircraft system FPL 37 Viggen, from 1977 to 2006. The analysis shows that the maintenance intervals are partly appropriate and that some performed changes are improvements. These conclusions are strengthened if the phase-out of the aircraft system is considered, where the preventive maintenance strategy has been replaced with a corrective one, in order to achieve cost-effectiveness. Considering the perfect repair assumption, it seems that the overhaul tasks essentially bring the items back to a state as good as new. The performed evaluation mostly considers when the failures are recognized, i.e. during operation or during maintenance. Hence, aspects such as item accessibility, personnel skill levels, and maintenance task intervals for other items are not included in the evaluation.

Silicon-Germanium for Phased Array Radars

Abstract: Phase and amplitude controlling ICs realized in a low cost standard silicon process are demonstrated. The design of several ICs at S-, C- and X-band has shown that silicon germanium is a strong contender to gallium arsenide where lowest noise figure is not vital. This applies also to the T/R-modules suited for military AESA-radars. The circuits presented in this paper are manufactured by austriamicrosystems in their 0.35 mum SiGe-BiCMOS process with an fT of 70 GHz.

Group invariance and L p -bounded operators

Abstract: The Hilbert and Riesz transforms can be characterized up to scalar as the translation invariant operators that satisfy additionally certain relative invariance of conformal transformation groups. In this article, we initiate a systematic study of translation invariant operators from group theoretic viewpoints, and formalize a geometric condition that characterizes specific multiplier operators uniquely up to scalar by means of relative invariance of affine subgroups. After providing some interesting examples of multiplier operators having “large symmetry”, we classify which of these examples can be extended to continuous operators on Lp(Rn) (1 < p < ∞).

The probability of near midair collisions using level-crossings

Abstract: We consider probabilistic methods to compute the near midair collision risk using state estimate and covariance from a target tracking filter based on angle-only sensors such as digital video cameras. Existing work is only concerned with risk estimation at a certain time instant, while the focus here is to compute the integrated risk over the critical time horizon. This novel formulation leads to evaluating the probability for level-crossing. The analytic expression for this involves a multi-dimensional integral which is hardly tractable in practice. Further, a huge number of Monte Carlo simulations would be needed to get sufficient reliability for the small risks that the applications require. Instead, we propose a sound numerical approximation that leads to a one-dimensional integral which is suitable for real-time implementations.

Response of electrified railway facilities to intentional electromagnetic interference: Review of research at Uppsala University

Abstract: A research program is being conducted at Uppsala University, Sweden, to investigate the possible susceptibility of civilian systems and networks to intentional electromagnetic interference (IEMI), with emphasis on the Swedish railway network. This paper reviews the details of the research program and some of the results.

Conceptual Design Using Generic Object Inheritance

Abstract: Conceptual design for complex products like aircraft and power plants requires a considerable effort since the product models become very large if they are to cover all important aspects for differ ...

Propagation ability of UWB transients through junctions of low-voltage power installation cable

Abstract: It has been shown earlier (D. Mansson et al., 2007) that ultra wide band (UWB) transients can travel in differential mode (DM) along low voltage power installation cables, and deliver large amounts of power to connected equipments. However, branches in the network were not included at that time. In this paper, the ability of UWB transients to propagate through different types of junctions of low voltage power cables is investigated. The received voltage could with very good accuracy be estimated from transmission line theory, either using theoretical calculations or numerical simulations. This was verified experimentally. The decrease in voltage received at the loads of the branches is mainly due to the reflection caused by impedance mismatch at the junction. It is concluded that large voltages can be delivered to unprotected loads, if a UWB transient is injected in DM at another part of the same network.

Demonstration of a formal method for incremental qualification of IMA systems

Abstract: In this paper we address the process of incremental certification/qualification of integrated modular avionic (IMA) systems. The work aims to show that given a scalable avionics architecture we can apply a component-based development process and save some safety analysis effort by reusing design models for components. This creates a formal framework for IMA system safety assessment.

Issues in connection to the prediction of strain localization in metal sheets

Abstract: The current paper deals with the prediction of strain localization in metal sheets. Especially the effect of strain rate dependency on the necking phenomenon is treated. The ability of FEM to predict strain localization during simulations of sheet forming operations is investigated. An approach for the determination of the strain rate material parameters, based on an experimentally determined FLD0, is suggested. The current approach is demonstrated for three sheet materials, and from the results the approach can be judged as promising.