Saab Automobile AB

About: Saab Automobile AB is a based out in . It is known for research contribution in the topics: Radar & Antenna (radio). The organization has 760 authors who have published 890 publications receiving 11811 citations.

Experience report: Memory accesses for avionic applications and operating systems on a multi-core platform

Abstract: The deployment of multi-core platforms in safety-critical avionic applications is hampered by the lack of means to ensure predictability when processes running on different cores can create interference effects, affecting worst-case execution time, due to shared memory accesses. One way to restrict these interferences is to allocate a budget for different processes prior to run-time and to monitor the adherence to this budget during run-time. While earlier works in adopting this approach seem promising, they focus on application level (user mode) accesses to shared memory and not the operating system accesses. In this paper we construct experiments for studying a multi-core platform running an ARINC 653 compliant operating system, and measure the impact of both application processes and operating system (supervisor mode) activities. In particular, as opposed to earlier works that considered networking applications, we select four avionic processes that exhibit different memory access patterns, namely, a navigation process, a matrix multiplication process, a math library process and an image processing one. The benchmarking on a set of avionic-relevant application processes shows that (a) the potential interference by the operating system cannot be neglected when allocating budgets that are to be monitored at run-time, and (b) the bounds for the allowed number of memory accesses should not always be based on the maximum measured count during profiling, which would lead to overly pessimistic budgets.

A Detector for Wavelength Resolution SAR Incoherent Change Detection

Abstract: This paper introduces an effective detector for wavelength-resolution SAR incoherent change detection. The detector is derived from Bayes' theorem. The input of the detector is the differences between surveillance and reference magnitude images simply obtained by a subtraction while the output is a summary of the detected changes. The proposed detector is tested with 24 CARABAS images that were obtained from the measurement campaign in northern Sweden in 2002. The testing results show that the detector can provide a high average detection probability, e.g., about 96%, with a very low false alarm rate, e.g., only 0.35 per square kilometer.

Derivation of Reaction Theorems for Scattered Fields

Abstract: Two novel formulations of the reaction are derived. The formulations decompose the electromagnetic fields in scattered components based on the location of the sources of the scattered fields. It is shown that some of the scattering components do not contribute to the reaction. The novel formulations of the reaction are derived by excluding these noncontributing components from the classical reaction formulations. The correctness of one of the formulations is verified with a numerical example. It is observed from one of the novel formulations that the first-order scattered fields do not contribute to the reaction. This result legitimizes the approximation to neglect multiple scattering, which is a common assumption when using reaction theorems. The novel formulations are also important for a conceptual understanding of the reaction.

Parametric investigation of low-dissipation low-dispersion schemes for unstructured flow solvers in large eddy simulation

Abstract: A second-order low-dissipation low-dispersion scheme is evaluated for unstructured finite-volume flow solvers. The scheme exploits a higher order central reconstruction of the face fluxes and a matrix dissipation formulation to reduce the dispersive and dissipative numerical errors. The scheme is applied using the M-Edge CFD solver for compressible flows for low-speed scale-resolving simulations. The scheme is shown to be a significant improvement to a conventional central scheme used for RANS simulations by accurately predicting reference DNS data for the plane channel flow and experimental data for the decaying homogenous isotropic turbulence.