Swedish Defence Research Agency

About: Swedish Defence Research Agency is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Radar & Synthetic aperture radar. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

G protection: interaction of straining maneuvers and positive pressure breathing.

Abstract: INTRODUCTION: G protection in the 39 Gripen aircraft is provided by a full coverage anti-G suit, a pressure-breathing system, and anti-G straining maneuvers (AGSM). The purpose was to study (1) the interaction of pressure breathing and AGSM while wearing an anti-G suit; and (2) the G-protective properties of the anti-G suit alone and in combination with the pressure-breathing system. METHODS: During rapid onset rate G-time profiles ( or = 6.5 Gz (4.5-9.0) in II, > or = 8.0 Gz (6.5-9.0) in III, > or = 8.9 Gz (8.5-9.0) in IV and > or = 9.0 Gz (8.5-9.0) in V. In the supplementary experiments, the anti-G suit afforded a 2.8-G protection, a third of which was contributed by the abdominal bladder. In the relaxed state, pressure applied to the airways was transmitted undistorted to the intrathoracic space. During AGSM, intrathoracic pressure rose to 10-14 kPa, regardless of whether AGSM was performed with or without pressure breathing. DISCUSSION: AND CONCLUSIONS: The anti-G suit and the pressure breathing system provide G protection of > or = 4.6 G, of which the anti-G suit contributes about 3.0 G. The C-protective properties of the anti-G suit and those of pressure breathing appears to be additive, whereas the G protection afforded by pressure breathing does not add to that provided by AGSM. Language: en

In situ gamma-ray spectrometry for environmental monitoring: a semi empirical calibration method.

Abstract: In situ gamma spectrometry using high-purity germanium (HPGe) detectors is a frequently used method for the determination of radionuclide ground deposition levels. Such measurements do, however, require an efficiency calibration based on detector sensitivity and parameters such as soil density and vertical activity distribution. In this work, a novel expression is used for the detector efficiency, incorporating both the influence of photon energy and incidence angle. Detector-specific efficiency data are determined empirically. For the theoretical calculation of the photon fluence at the detector, a three-layer model of finite thickness is developed for the description of soil density and vertical activity distribution. In order to facilitate the calibration of in situ measurements, a PC program has been developed to enable rapid, on-site calculations of radionuclide ground deposition levels. The semi empirical calibration method was tested on in situ measurements with two different detectors, and the results show good agreement with results obtained from traditional soil sampling.

Data collection and simulation of high range resolution laser radar for surface mine detection

Abstract: Rapid and efficient detection of surface mines, IED's (Improvised Explosive Devices) and UXO (Unexploded Ordnance) is of high priority in military conflicts. High range resolution laser radars combined with passive hyper/multispectral sensors offer an interesting concept to help solving this problem. This paper reports on laser radar data collection of various surface mines in different types of terrain. In order to evaluate the capability of 3D imaging for detecting and classifying the objects of interest a scanning laser radar was used to scan mines and surrounding terrain with high angular and range resolution. These data were then fed into a laser radar model capable of generating range waveforms for a variety of system parameters and combinations of different targets and backgrounds. We can thus simulate a potential system by down sampling to relevant pixel sizes and laser/receiver characteristics. Data, simulations and examples will be presented.

A Mixed Integer Linear Programming approach to pursuit evasion problems with optional connectivity constraints

Abstract: In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. By discretizing the problem, and applying a Mixed Integer Linear Programming (MILP) framework, we are able to address problems requiring so-called recontamination and also impose additional constraints, such as connectivity between the pursuers. The proposed MILP formulation is less conservative than solutions based on graph discretizations of the environment, but still somewhat more conservative than the original underlying problem. It is well known that MILPs, as well as multi pursuer pursuit evasion problems, are NP-hard. Therefore we apply an iterative Receding Horizon Control (RHC) scheme where a number of smaller MILPs are solved over shorter planning horizons. The proposed approach is implemented in Matlab/Cplex and illustrated by a number of solved examples.

The Nature of Infrasystem Services

Abstract: Infrasystems are the large technical systems in society delivering water and electricity, making communications and transports possible, managing the gathering and treatment of refuse and sewage, and many other services. Infrasystems mean welfare, convenience and economic growth, but also considerable environmental impacts. The overall aim of this thesis is to contribute to the development of aspects and prerequisites of infrasystem change in a sustainable direction, by way of elaborating conceptual knowledge. The first main point of departure is the concept of infrasystem, and the related approach Large Technical Systems (LTS), primarily associated the field of history of technology. A key feature is to highlight a socio-technical systems perspective, rather than separating technology from social and institutional aspects. The second main point of departure is the change perspective Situations of Opportunity (SITOP), which is a draft theory developed within a research programme at the Royal Institute of Technology. SITOP set out from the notion that the possibility to implement changes in a sustainable direction is greater than average at certain moments in time. A situation of opportunity is associated with a prehistory, limiting the field of options for the actors utilising a formative moment. When SITOP, LTS and other related socio-technical perspectives are cross-fertilised some directions of where to look for future situations of opportunity for infrasystem change in a sustainable direction can be pointed out, e.g. in connection with certain problems or crises in the systems’ development. On the one hand different aspects on how to widen the field of options are discussed, e.g. to promote inter-sectorial actor networks, to identify system synergies and social innovations (paper 1-3), and to highlight services and functions rather than sectors and technology (paper 2). On the other hand, in order to approach the great changes needed in the context of sustainable development, the socio-technical regimes of today have to undergo major alterations, which probably presupposes new sets of actors and actor networks. A more moderate view however, is to seek positive synergies between everyday decision- and policy-making and the long-term striving for sustainable development. Issues often considered as necessities, e.g. renovations of old buildings, or building more roads to moderate congestion – ‘what must be done’ – should be combined with ‘what should be done’, e.g. implementing energy saving solutions in the built environment, or reducing society’s transport dependency. The array of conceivable combinations widens the field of options. The results also concern indirect effects of infrasystems, which might contribute to processes evaluating fields of options. Infrastructure investments affect activity patterns and the built environment (paper 4). Moreover infrasystems are associated with indirect energy use (paper 5). The conceptual views presented in this thesis are no immediate means, ready to be used in concrete infrasystem management, but can in the steps that follow primary policy-making support the process of finding out when to implement change, and moreover assessing plausible solutions. In other words – identify situations of opportunity and explore the field of options.