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.

Evaluating Strategies for Defending Electric Power Networks Against Antagonistic Attacks

Abstract: We show how concepts from game theory can be used to find and evaluate strategies for defending an electric power system against antagonistic attacks. Consequently, the interaction between the antagonist and the defender of the system is envisaged as a game. In a numerical example, we study the performance of different defense strategies against a number of attack scenarios. Particularly, we study whether there is a dominant defense strategy and an optimal allocation of resources between protection of components and recovery

Cirene: Air—Sea Interactions in the Seychelles—Chagos Thermocline Ridge Region

Abstract: The Vasco-Cirene program explores how strong air-sea interactions promoted by the shallow thermocline and high sea surface temperature in the Seychelles-Chagos thermocline ridge results in marked variability at synoptic, intraseasonal, and interannual time scales. The Cirene oceanographic cruise collected oceanic, atmospheric, and air-sea flux observations in this region in January–February 2007. The contemporaneous Vasco field experiment complemented these measurements with balloon deployments from the Seychelles. Cirene also contributed to the development of the Indian Ocean observing system via deployment of a mooring and 12 Argo profilers. Unusual conditions prevailed in the Indian Ocean during January and February 2007, following the Indian Ocean dipole climate anomaly of late 2006. Cirene measurements show that the Seychelles-Chagos thermocline ridge had higher-than-usual heat content with subsurface anomalies up to 7°C. The ocean surface was warmer and fresher than average, and unusual eastward cur...

Discrimination of Nuclear Explosions against Civilian Sources Based on Atmospheric Xenon Isotopic Activity Ratios

Abstract: A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System that will verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) once the treaty has entered into force. This paper studies isotopic activity ratios to support the interpretation of observed atmospheric concentrations of 135Xe, 133mXe, 133Xe and 131mXe. The goal is to distinguish nuclear explosion sources from civilian releases. Simulations of nuclear explosions and reactors, empirical data for both test and reactor releases as well as observations by measurement stations of the International Noble Gas Experiment (INGE) are used to provide a proof of concept for the isotopic ratio based method for source discrimination.

2D empirical mode decompositions in the spirit of image compression

Abstract: The Empirical mode decomposition (EMD) is an adaptive decomposition of the data, as is the Wavelet packet best basis decomposition. This work present the first attempt to examining the use of EMD for image compression purposes. The Intrinsic Mode Function (IMF) and their Hilbert spectra are compared to the wavelet basis and the wavelet packet decompositions expanded in each of its best bases on the same data. By decomposing the signal into basis functions, the waveforms in the signal is represented by the basis and a set of decorrelated discrete values in a vector. A coding scheme is presented where the idea is to decompose the signal into its IMF:s where only the max and min values for each IMF is transmitted. The reconstruction of the IMF in the decoder is done with spline interpolation. We have in the two-dimensional EMD an adaptive image decomposition without the limitations from filter kernels or cost functions. The IMF:s are, in the two-dimensional case, to be seen as spatial frequency subbands, with various center frequency and bandwidth along the image.