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 & Laser. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

Emission Factors for Gases and Particle-Bound Substances Produced by Firing Lead-Free Small-Caliber Ammunition

Abstract: Lead-free ammunition is becoming increasingly popular because of the environmental and human health issues associated with the use of leaded ammunition. However, there is a lack of data on the emissions produced by firing such ammunition. We report emission factors for toxic gases and particle-bound compounds produced by firing lead-free ammunition in a test chamber. Carbon monoxide, ammonia, and hydrogen cyanide levels within the chamber were analysed by Fourier transform infrared spectroscopy, while total suspended particles and respirable particles were determined gravimetrically. The metal content of the particulate emissions was determined and the associated organic compounds were characterized in detail using a method based on thermal desorption coupled to gas chromatography and mass spectrometry. The particulate matter (∼30 mg/round) consisted primarily of metals such as Cu, Zn, and Fe along with soot arising from incomplete combustion. Nitrogen-containing heterocyclic aromatic compounds such as ca...

Explicit algebraic Reynolds stress and non-linear eddy-viscosity models

Abstract: This article reviews explicit algebraic Reynolds stress models and other non-linear eddy-viscosity turbulence models utilised in the context of Reynolds-Averaged Navier-Stokes simulations of turbulent flows. Since the 1990s, these modelling classes have become important intermediate classes between the linear eddy viscosity models and full Reynolds stress transport models. The derivation of explicit algebraic Reynolds stress models from the Reynolds stress transport models, and the required simplifications are discussed. The most important simplification is the weak-equilibrium assumption. Properties of the basic weak-equilibrium assumption and its extended form are discussed. Differences between explicit solutions based on complete tensor representation and those based on reduced representation as well as other non-linear eddy-viscosity models are pointed out. The scale-determining models are also discussed briefly.

Distribution, Chemical Speciation, and Mobility of Lead and Antimony Originating from Small Arms Ammunition in a Coarse-Grained Unsaturated Surface Sand

Abstract: This study quantified the heavy metal contamination caused by firing 500 high-velocity 7.62-mm jacketed Swedish military rounds. Contamination of solid and aqueous phases was studied, with Pb and Sb being the two contaminants of primary interest. The distribution of the Pb and Sb were measured in terms of depth of penetration in sand and grain size distribution of the bullet particles. The Pb- and Sb-contaminated sand was then used as a source material in two bench-scale unsaturated lysimeters to measure the transport of Pb and Sb through two coarse-grained sands, which were taken from the berms on two Swedish military small arms ranges. The lysimeters were subjected to an infiltration cycle that reproduced spring snowmelt, which is the most significant infiltration event of the year in northern climates. The levels of mobile Pb and Sb were monitored in the effluent from the lysimeters. Extended X-ray absorption fine-structure spectroscopy analysis was performed on the contaminated sands to determine Pb speciation before and after leaching. Ninety-three percent of the mass of bullets was found in the top 30 cm of sand. Lead oxide was the predominant species of Pb before and after leaching. Transport of Pb was small, with aqueous concentrations remaining stable at <2 microg L(-1). Antimony was far more mobile, with solute breakthrough occurring between 5 and 14 d and concentrations rising to over 125 microg L(-1) within 1 month.

Early treatment of chlorine-induced airway hyperresponsiveness and inflammation with corticosteroids.

Abstract: Chlorine (Cl2) is an industrial gas that is highly toxic and irritating when inhaled causing tissue damage and an acute inflammatory response in the airways followed by a long-term airway dysfunction. The aim of this study was to evaluate whether early anti-inflammatory treatment can protect against the delayed symptoms in Cl2-exposed mice. BALB/c mice were exposed by nose-only inhalation using 200 ppm Cl2 during 15 min. Assessment of airway hyperresponsiveness (AHR), inflammatory cell counts in bronchoalveolar lavage, occurrence of lung edema and lung fibrosis were analyzed 24 h or 14 days post-exposure. A single dose of the corticosteroid dexamethasone (10 or 100 mg/kg) was administered intraperitoneally 1, 3, 6, or 12 h following Cl2 exposure. High-dose of dexamethasone reduced the acute inflammation if administered within 6 h after exposure but treated animals still displayed a significant lung injury. The effect of dexamethasone administered within 1 h was dose-dependent; high-dose significantly reduced acute airway inflammation (100 mg/kg) but not treatment with the relatively low-dose (10 mg/kg). Both doses reduced AHR 14 days later, while lung fibrosis measured as collagen deposition was not significantly reduced. The results point out that the acute inflammation in the lungs due to Cl2 exposure only partly is associated with the long-term AHR. We hypothesize that additional pathogenic mechanisms apart from the inflammatory reactions contribute to the development of long-term airway dysfunction. By using this mouse model, we have validated early administration of corticosteroids in terms of efficacy to prevent acute lung injury and delayed symptoms induced by Cl2 exposure.

Countering laser pointer threats to road safety.

Abstract: The market demand for bright laser pointers has led to the development of readily available devices that can pose a threat to road safety. Laser pointers can be involved in accidents caused by laser users who do not realise the dangers involved, but laser pointers can also enable deliberate criminal activity. There are technologies available that can counter the threat in different ways. A number of protective principles are outlined below. Some technologies built upon Liquid Crystal Devices are described in greater detail. Without any knowledge of what laser pointers a potential aggressor has access to, a frequency agile filter seems to be the most promising way to avoid the most severe consequences of dazzle from laser pointers. Protective systems incorporating suitable glasses or visors holding frequency agile filters of this kind however, are not commercially available today.