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.

Mass Flow Boundary Conditions for Subsonic Inflow and Outflow Boundary

Abstract: This dissertation deals with the development of the vortex generator model and its use for the optimization study of vortex generator flow control in high-offset-ed inlets. In the first part, the overview of use of vortex generators and their mechanism is outlined. Both the application form the existing aircraft as well as laboratory studies are reviewed. The second part contains four papers. The first paper deals with the development, verification and validation of the vortex generator model in Navier-Stokes code. Although primarily meant to be used in inlets, the validation of the model was carried out in case of high-lift system by comparing pressure coefficient to the experimental data. Second paper deals with development of the inflow and outflow mass flow boundary conditions for Navier-Stokes codes. Newly designed mass flow boundary conditions were compared to existing mass flow boundary conditions. Special attention was paid to flows under condition of choking. Third paper deals with the Design of Experiment optimization study of the vortex generator flow control in the RAE M2129 inlet with two sets of five geometrical parameters. The aim is to reduce the inlet flow distortion and increase pressure recovery. The parameters of optimal vortex generator setup were then used to design a vortex generator flow control in more realistic inlet for a UAV. Fourth paper deals with testing of vortex generator flow control in the UAV inlet under different flight conditions. In order to be able to find appropriate parameters of flow in inlet, entire UAV with prescribed value of the mass flow was calculated. It was found that the proposed vortex generator installation malfunctioned when at conditions corresponding to the high altitude flight conditions. A new configuration with double number of vortex generators was then tested and at proven being stable. Triangular vortex generators were tested also.

Oligodeoxynucleotides containing CpG motifs can induce T cell-dependent arthritis in rats.

Abstract: Objective To investigate whether CpG oligodeoxynucleotides (ODNs) can induce or accelerate arthritis in rats. Methods The CpG-induced response was studied by recording joint inflammation, cell activation in draining lymph nodes, and levels of the acute-phase reactant α1-acid glycoprotein (AGP) in sera. The role of T cells was investigated by in vivo administration of monoclonal antibodies specific for the T cell receptor α/β (TCRα/β), followed by analysis of cell phenotypes by flow cytometry. Results One intradermal injection of CpG ODN emulsified with Freund's incomplete adjuvant (IFA) induced arthritis in LEW and LEW.1AV1 rats, while the control ODN sequence without CpG motifs or IFA alone did not trigger disease. The CpG/IFA and control-ODN/IFA injections induced lymphoplasia as well as elevated levels of interleukin-1β and interferon-γ messenger RNA in lymph nodes. The arthritis was preceded by elevated levels of AGP in serum. In vivo administration of anti-TCRα/β antibodies after disease induction caused decreased expression of the TCR–CD3 complex on circulating T cells and ameliorated the arthritis. Conclusion We demonstrated that injection with immunostimulatory CpG, both in phosphorothioate-modified and native forms, can induce a T cell–dependent joint-specific inflammation in LEW and LEW.1AV1 rat strains. This arthritis is preceded by signs of activation of the innate immune system. Since unmethylated CG dinucleotides are common in bacterial DNA but rare in mammalian DNA, our results indicate that exposure to bacterial DNA during infection may contribute to arthritis induction by amplifying the innate immune response.

Synthesis and nonlinear light scattering of microemulsions and nanoparticle suspensions

Abstract: Microemulsions composed of normal or inverse micellar solutions and aqueous suspensions of pristine (uncoated) or silica-coated iron oxide nanoparticles, mainly γ-Fe2O3, were synthesised and their optical limiting properties investigated. The microemulsions are colorless solutions with high transparency for visible wavelengths while the aqueous suspensions of iron oxide are of pale yellow colour. Optical limiting experiments performed in 2 mm cells using a f/5 optical system with a frequency doubled Nd:YAG laser delivering 5 ns pulses with 10 Hz repetition rate, showed clamping levels of ∼3 μJ for the suspensions of both pristine and silica-coated iron oxide nanoparticles. A strong photoinduced nonlinear light scattering was observed for the water-in-oil microemulsion and the aqueous suspensions of nanoparticles while oil-in-water microemulsions did not show a significant nonlinear effect. Measurements carried out using an integrating sphere further verified that the photoinduced nonlinear light scattering is the dominating nonlinear mechanism while the nonlinear absorption of iron oxide nanoparticles is negligible at 532 nm.

Measurements of Faraday Rotation Using Polarimetric PALSAR Images

Abstract: For spaceborne synthetic aperture radar (SAR) systems operating at L-band frequencies or lower, the ionosphere may have a significant impact on the SAR images. The largest effect at L-band is caused by Faraday rotation (FR). Several studies have modeled the effect of FR and/or devised models to measure and correct FR. With the launch of the fully polarimetric L-band system Phased Array-type L-band SAR (PALSAR), it has become possible to test both models and measurement techniques on real SAR data. In this letter, the quality of calibrated polarimetric PALSAR data is assessed, and FR is measured. It is found that residual crosstalk and channel imbalance are small in the PALSAR data. Two methods are used to measure FR, the first using in-scene distributed targets and the second using large trihedrals. The two methods show very good agreement. The measurements are compared with values of the total electron content using a linear model. It is found that the model and measurements are in good agreement, with a root-mean-square error of 0.3deg or 15% of the mean FR angle.