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Synthetic Aperture Radar is a form of radar widely used to extract information about the surface of the target. The transformation of the signals into an image is based on DSP algorithms that perform intensive but repetitive computation over the signal data. Traditionally, an aircraft or satellite acquires the radar data streams and sends it to be processed on a data center to produce images faster. However, there are novel applications demanding on-board signal processing to generate images. This paper presents a novel implementation for an on-board embedded SoC of an accelerator for the Backprojection algorithm, which is the reference algorithm for producing images of SAR sensors. The methodology used is based on a HW/SW design partition, where the most time consuming computations are implemented in hardware. The accelerator was specified in HLS, which allows to reuse the code from the original implementation of the algorithm in software. The accelerator performs the computations using floating-point arithmetic to produce the same output as the original algorithm. The target SoC device is a Zynq 7020 from Xilinx which has a dual-core ARM-A9 processor along with a reconfigurable fabric which is used to implement the hardware accelerator. The proposed systems outperformed the software-only implementation in 7.7\(\times \) while preserving the quality of the image by adopting the same floating-point representations from the original software implementation.

In this research work, an on-board dual-core embedded architecture was developed for SAR imaging systems, implementing a reduced-precision redundancy fault-tolerance mechanism. This architecture protects the execution of the BackProjection Algorithm, capable of generating acceptable SAR images in embedded systems subjected to errors from the space environment. The proposed solution was implemented on a Xilinx SoC device with a dual-core processor. The present work was able to produced images with less 0.65 dB on average, than the fault-free image, at the expense of a time overhead up to 33%, when in the presence of error rates similar to the ones measured in space environment. Notwithstanding, the BackProjection algorithm executed up to 1.58 times faster than its single-core version without any fault-tolerance mechanisms.

Extending life of existing structures should be supported by guidelines or technical rules. In the case of historic buildings, besides the technical, economic and social aspects to be taken into account, the historic importance may determine the level of intervention to be performed. In spite of that, the integrity of the building itself and protection to people must be safeguarded and structural safety must reach a minimum level. However, safety requirements are not always established. Some European countries have national regulations and standards regarding assessment and retrofitting of existing structures. There is a need for harmonised European technical rules on this subject which can be broadly accepted. This paper refers the existing design codes and the work under way to extend them to existing structures and discusses their application and limitations regarding historic buildings. Based on LNEC experience, an approach is also proposed concerning the safety requirements applicable to heritage buildings, discussing the suitability of specifying different target reliability levels. Those levels should depend on the heritage value of the structure and the consequences of a possible failure of the structure, thus linked to its acceptable use.