Techniques to improve the reliability of fault-tolerant systems based on self-reconfigurable FPGAs

In this paper it is proposed a new technique toimprove the reliability of fault-tolerant systemsbased on self-reconfigurable FPGAs. The aim is tocreate a self-tolerant system based on selfreconfiguration.To achieve this objective the workwas divided in five main tasks: the analysis of faultinducement mechanisms in FPGAs, its correlationand its matching with existent fault models, or,eventually, if necessary, the proposal of a newmodel; the design and evaluation of a fault tolerancemechanism for FPGAs; the design andimplementation of a methodology able to detect,diagnose and repair the emerging faults; thedevelopment and validation of the proposedmethodology. This study will be the base for a PhDthesis

The role of Dark Matter interaction in galaxy clusters

We consider a toy model to analyze the consequences of dark matter interaction with a dark energy background on the overall rotation of galaxy clusters and the misalignment between their dark matter and baryon distributions when compared to {\Lambda}CDM predictions. The interaction parameters are found via a genetic algorithm search. The results obtained suggest that interaction is a basic phenomenon whose effects are detectable even in simple models of galactic dynamics.Comment: RevTeX 4.1, 5 pages, 3 figure

A loose-coupled fusion of inertial and UWB assisted by a decision-making algorithm for localization of emergency responders

Combining different technologies is gaining significant popularity among researchers and industry for the development of indoor positioning systems (IPSs). These hybrid IPSs emerge as a robust solution for indoor localization as the drawbacks of each technology can be mitigated or even eliminated by using complementary technologies. However, fusing position estimates from different technologies is still very challenging and, therefore, a hot research topic. In this work, we pose fusing the ultrawideband (UWB) position estimates with the estimates provided by a pedestrian dead reckoning (PDR) by using a Kalman filter. To improve the IPS accuracy, a decision-making algorithm was developed that aims to assess the usability of UWB measurements based on the identification of non-line-of-sight (NLOS) conditions. Three different data fusion algorithms are tested, based on three different time-of-arrival positioning algorithms, and experimental results show a localization accuracy of below 1.5 m for a 99th percentile.This work has been partially supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019 and Project UID/CTM/00264/2019 of 2C2T - Centro de Ciência e Tecnologia Têxtil, funded by National Founds through FCT/MCTES. The work of A. G. Ferreira and D. Fernandes was supported by the FCT under Grant SFRH/BD/91477/2012 and Grant SFRH/BD/92082/2012

Real-time fault injection using enhanced on-chip debug infrastructures

The rapid increase in the use of microprocessor-based systems in critical areas, where failures imply risks to human lives, to the environment or to expensive equipment, significantly increased the need for dependable systems, able to detect, tolerate and eventually correct faults. The verification and validation of such systems is frequently performed via fault injection, using various forms and techniques. However, as electronic devices get smaller and more complex, controllability and observability issues, and sometimes real time constraints, make it harder to apply most conventional fault injection techniques. This paper proposes a fault injection environment and a scalable methodology to assist the execution of real-time fault injection campaigns, providing enhanced performance and capabilities. Our proposed solutions are based on the use of common and customized on-chip debug (OCD) mechanisms, present in many modern electronic devices, with the main objective of enabling the insertion of faults in microprocessor memory elements with minimum delay and intrusiveness. Different configurations were implemented starting from basic Components Off-The-Shelf (COTS) microprocessors, equipped with real-time OCD infrastructures, to improved solutions based on modified interfaces, and dedicated OCD circuitry that enhance fault injection capabilities and performance. All methodologies and configurations were evaluated and compared concerning performance gain and silicon overhead

Flexible Blue-Light Fiber Amplifiers to Improve Signal Coverage in Advanced Lighting Communication Systems

Visible-light communication (VLC) based on white light-emitting diodes has recently attracted much attention to provide high-bitrate data communication in indoor environments. One of the remaining challenges to be resolved to enable the proliferation of VLC systems is related to channel attenuation and multiple path fading. Here, we introduce an advanced VLC system integrating an optical amplifier as a promising solution to overcome channel impairments, providing high bitrate coverage. The optical amplifier is a flexible fiber based on a poly(fluorene)-based lumophore doped within a di-ureasil organic-inor- ganic hybrid. Optical amplification is demonstrated for pre-amplifier and relay node scenarios, yielding a maximum gain of 5.9 G 0.2 dB and 3.7 G 0.2 dB, respectively, establishing the proposed approach as a promising cost-effective solution for VLCs. Additionally, numerical simulations show, for a realistic envi- ronment, a 207% improvement in the coverage area, using existing lighting infrastructure without extra cost.R.C.E. acknowledges funding from the European Research Council (ERC) under the European Union’s Ho- rizon 2020 research and innovation programme (grant agreement no. 818762 - SPECTRACON)

Open-source software product line extraction processes: the ArgoUML-SPL and Phaser cases

Software Product Lines (SPLs) are rarely developed from scratch. Commonly, they emerge from one product when there is a need to create tailored variants, or from existing variants created in an ad-hoc way once their separated maintenance and evolution become challenging. Despite the vast literature about re-engineering systems into SPLs and related technical approaches, there is a lack of detailed analysis of the process itself and the effort involved. In this paper, we provide and analyze empirical data of the extraction processes of two open source case studies, namely ArgoUML and Phaser. Both cases emerged from the transition of a monolithic system into an SPL. The analysis relies on information mined from the version control history of their respective source-code repositories and the discussion with developers that took part in the process. Unlike previous works that focused mostly on the structural results of the final SPL, the contribution of this study is an in-depth characterization of the processes. With this work, we aimed at providing a deeper understanding of the strategies for SPL extraction and their implications. Our results indicate that the source code changes can range from almost a fourth to over half of the total lines of code. Developers may or may not use branching strategies for feature extraction. Additionally, the problems faced during the extraction process may be due to lack of tool support, complexity on managing feature dependencies and issues with feature constraints. We made publicly available the datasets and the analysis scripts of both case studies to be used as a baseline for extractive SPL adoption research and practice.This research was partially funded by CNPq, grant no. 408356/2018-9; FAPPR, grant no. 51435; and FAPERJ PDR-10 Fellowship 202073/2020. Open access funding provided by Johannes Kepler University Lin

Universal behavior at discontinuous quantum phase transitions

Discontinuous quantum phase transitions besides their general interest are clearly relevant to the study of heavy fermions and magnetic transition metal compounds. Recent results show that in many systems belonging to these classes of materials, the magnetic transition changes from second order to first order as they approach the quantum critical point (QCP). We investigate here some mechanisms that may be responsible for this change. Specifically the coupling of the order parameter to soft modes and the competition between different types of order near the QCP. For weak first order quantum phase transitions general results are obtained. In particular we describe the thermodynamic behavior at this transition when it is approached from finite temperatures. This is the discontinuous equivalent of the non-Fermi liquid trajectory close to a conventional QCP in a heavy fermion material.Comment: 7 pages, 3 figure