Error-efficient computing systems

This survey explores the theory and practice of techniques to make computing systems faster or more energy-efficient by allowing them to make controlled errors. In the same way that systems which only use as much energy as necessary are referred to as being energy-efficient, you can think of the class of systems addressed by this survey as being error-efficient: They only prevent as many errors as they need to. The definition of what constitutes an error varies across the parts of a system. And the errors which are acceptable depend on the application at hand. In computing systems, making errors, when behaving correctly would be too expensive, can conserve resources. The resources conserved may be time: By making some errors, systems may be faster. The resource may also be energy: A system may use less power from its batteries or from the electrical grid by only avoiding certain errors while tolerating benign errors that are associated with reduced power consumption. The resource in question may be an even more abstract quantity such as consistency of ordering of the outputs of a system. This survey is for anyone interested in an end-to-end view of one set of techniques that address the theory and practice of making computing systems more efficient by trading errors for improved efficiency

Report of the IEEE Workshop on Measurement and Modeling of Computer Dependability

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNASA Langley Research Center / NASA NAG-1-602 and NASA NAG-1-613ONR / N00014-85-K-000

Fault injection for the evaluation of critical systems

Dissertação de mestrado em Engenharia InformáticaAtualmente, os sistemas críticos estão cada vez mais presentes no nosso dia-a-dia, fazendo aumentar a necessidade de os assegurar cada vez mais e reduzindo o risco de acidente ou falha. A industria espacial e automóvel são exemplos de indústrias que usam esses sistemas e que necessitam de os ver assegurados. Consequentemente, têm de ser tomadas medidas para garantir a segurança de um sistema ao nível de software e hardware. A injeção de falhas é uma das respostas a esse problema, fazendo uso das suas diferentes técnicas para poder avaliar e validar sistemas críticos. A injeção de falhas pode ser considerada uma técnica de teste ao software, onde as falhas podem ser injetadas ao nível do software ou hardware e cujos resultados podem ser monitorizados de forma a avaliar como é que o sistema reagiu a tais falhas. Scan-Chain Implemented Fault Injection é a técnica de injeção de falhas que proporciona uma maior acessibilidade, observabilidade e controlabilidade. Com esta técnica, os níveis de hardware e de integração de sistemas podem ser validados. O csXception® é um ambiente de injeção de falhas automatizado desenvolvido pela Critical Software S.A para avaliar e validar sistemas críticos. A sua arquitetura é dinâmica e baseada em plug-ins de injeção de falhas. Devido à crescente presença dos microcontroladores ARM® Cortex-M3 na industria automóvel, surgiu a necessidade de criar um novo plug-in de injeção de falhas para o csXception®. Assim, o objectivo principal desta dissertação de mestrado é o desenvolvimento de um novo plug-in de injeção de falhas para o csXception®, que permita injetar falhas em microcontroladores ARM® Cortex-M3, contextualizar o novo plug-in com a norma ISO-26262 e utilizar um caso de estudo para mostrar alguns dos resultados obtidos.Nowadays, critical systems are much more present in our daily life, increasing the need to ensure that these systems are becoming safer and thus reducing the risk of accident or failure. The space and automotive industry are examples of industries who use these systems and need to see them insured. Therefore, actions need to be taken to guarantee the safety of a system, both at software and hardware levels. Fault injection is one of the answers to that specific problem, making use of its different techniques in order to respond to the critical system validation and evaluation. Fault injection can be considered as a testing technique, where faults are injected in the hardware or software levels and whose results are monitored in order to evaluate how the system handles such faults. Scan-Chain Implemented Fault Injection is a fault injection technique that provides more reachability, observability and controllability. With this technique, the hardware-level and system-integration validation can be guaranteed. csXception® is an automated fault injection environment that validates and evaluates critical systems. Developed by Critical Software, S.A., the csXception®'s architecture is dynamic and based on fault injection plug-ins. With the increasing presence of Cortex-M3 microcontrollers on the automotive industry, a new plug-in for csXception® needs to be developed. Thus, the main goal of this master dissertation is the development of a new fault injection plug-in for csXception® that allows the user to inject faults into ARM® Cortex-M3 microcontrollers, to contextualize the new plug-in with the ISO-26262 safety standards and to use a case study to show some of the obtained results

Certifications of Critical Systems – The CECRIS Experience

In recent years, a considerable amount of effort has been devoted, both in industry and academia, to the development, validation and verification of critical systems, i.e. those systems whose malfunctions or failures reach a critical level both in terms of risks to human life as well as having a large economic impact.Certifications of Critical Systems – The CECRIS Experience documents the main insights on Cost Effective Verification and Validation processes that were gained during work in the European Research Project CECRIS (acronym for Certification of Critical Systems). The objective of the research was to tackle the challenges of certification by focusing on those aspects that turn out to be more difficult/important for current and future critical systems industry: the effective use of methodologies, processes and tools.The CECRIS project took a step forward in the growing field of development, verification and validation and certification of critical systems. It focused on the more difficult/important aspects of critical system development, verification and validation and certification process. Starting from both the scientific and industrial state of the art methodologies for system development and the impact of their usage on the verification and validation and certification of critical systems, the project aimed at developing strategies and techniques supported by automatic or semi-automatic tools and methods for these activities, setting guidelines to support engineers during the planning of the verification and validation phases

Certifications of Critical Systems – The CECRIS Experience

In recent years, a considerable amount of effort has been devoted, both in industry and academia, to the development, validation and verification of critical systems, i.e. those systems whose malfunctions or failures reach a critical level both in terms of risks to human life as well as having a large economic impact.Certifications of Critical Systems – The CECRIS Experience documents the main insights on Cost Effective Verification and Validation processes that were gained during work in the European Research Project CECRIS (acronym for Certification of Critical Systems). The objective of the research was to tackle the challenges of certification by focusing on those aspects that turn out to be more difficult/important for current and future critical systems industry: the effective use of methodologies, processes and tools.The CECRIS project took a step forward in the growing field of development, verification and validation and certification of critical systems. It focused on the more difficult/important aspects of critical system development, verification and validation and certification process. Starting from both the scientific and industrial state of the art methodologies for system development and the impact of their usage on the verification and validation and certification of critical systems, the project aimed at developing strategies and techniques supported by automatic or semi-automatic tools and methods for these activities, setting guidelines to support engineers during the planning of the verification and validation phases

Modelling of the Electric Vehicle Charging Infrastructure as Cyber Physical Power Systems: A Review on Components, Standards, Vulnerabilities and Attacks

The increasing number of electric vehicles (EVs) has led to the growing need to establish EV charging infrastructures (EVCIs) with fast charging capabilities to reduce congestion at the EV charging stations (EVCS) and also provide alternative solutions for EV owners without residential charging facilities. The EV charging stations are broadly classified based on i) where the charging equipment is located - on-board and off-board charging stations, and ii) the type of current and power levels - AC and DC charging stations. The DC charging stations are further classified into fast and extreme fast charging stations. This article focuses mainly on several components that model the EVCI as a cyberphysical system (CPS)

Future Challenges and Mitigation Methods for High Photovoltaic Penetration: A Survey

: Integration of high volume (high penetration) of photovoltaic (PV) generation with power grids consequently leads to some technical challenges that are mainly due to the intermittent nature of solar energy, the volume of data involved in the smart grid architecture, and the impact power electronic-based smart inverters. These challenges include reverse power flow, voltage fluctuations, power quality issues, dynamic stability, big data challenges and others. This paper investigates the existing challenges with the current level of PV penetration and looks into the challenges with high PV penetration in future scenarios such as smart cities, transactive energy, proliferation of plug-in hybrid electric vehicles (PHEVs), possible eclipse events, big data issues and environmental impacts. Within the context of these future scenarios, this paper reviewed the existing solutions and provides insights to new and future solutions that could be explored to ultimately address these issues and improve the smart grid’s security, reliability and resilienc