A Survey on Cache Management Mechanisms for Real-Time Embedded Systems

© ACM, 2015. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Computing Surveys, {48, 2, (November 2015)} http://doi.acm.org/10.1145/2830555Multicore processors are being extensively used by real-time systems, mainly because of their demand for increased computing power. However, multicore processors have shared resources that affect the predictability of real-time systems, which is the key to correctly estimate the worst-case execution time of tasks. One of the main factors for unpredictability in a multicore processor is the cache memory hierarchy. Recently, many research works have proposed different techniques to deal with caches in multicore processors in the context of real-time systems. Nevertheless, a review and categorization of these techniques is still an open topic and would be very useful for the real-time community. In this article, we present a survey of cache management techniques for real-time embedded systems, from the first studies of the field in 1990 up to the latest research published in 2014. We categorize the main research works and provide a detailed comparison in terms of similarities and differences. We also identify key challenges and discuss future research directions.King Saud University NSER

AVALIAÇÃO DOS TEORES DE ºBRIX, PH E PERDA DE MASSA EM DIFERENTES TIPOS DE PROCESSAMENTO MÍNIMO DE LARANJA UMBIGO (CITRUS SINENSIS): RELATO DE AULA PRÁTICA

As perdas na produção de laranja e outros produtos da horticultura podem somar, até chegar no consumidor final, uma perda de 50% da produção e estas perdas sairão do lucro que iria se obter com sua comercialização. Pensando deste modo, faz-se necessário descobrir métodos e tecnologias para diminuir estas perdas. Assim, foram realizados dois tipos de processamentos mínimos em laranjas umbigo (Citrus sinesis) a fim de descobrir qual a variação nos teores de ºBrix, pH, porcentagem de Ácido Cítrico/mL, Perda de Massa e valor de Ratio. Foram utilizadas laranjas médias em cada tipo de processamento mínimo, sendo que um processamento foi realizado padrão colheita e outros dois métodos de processamento mínimo. As frutas foram descascadas e fatiadas, embaladas, pesadas e levadas a um refrigerador. Após sete dias foram pesadas e avaliadas. Pelo ratio, observa-se que as frutas processadas logo após colheita apresentaram os melhores teores de Brix e pH na comparação com os teores das laranjas que foram processadas (inteiras e em fatias). O processamento mínimo de laranjas inteiras obteve menos perdas de massa e maior teor de ºBrix

Byzantine Resilient Protocol for the IoT

Wireless sensor networks, often adhering to a single gateway architecture, constitute the communication backbone for many modern cyber-physical systems. Consequently, faulttolerance in CPS becomes a challenging task, especially when accounting for failures (potentially malicious) that incapacitate the gateway or disrupt the nodes-gateway communication, not to mention the energy, timeliness, and security constraints demanded by CPS domains. This paper aims at ameliorating the fault-tolerance of WSN based CPS to increase system and data availability. To this end, we propose a replicated gateway architecture augmented with energy-efficient real-time Byzantineresilient data communication protocols. At the sensors level, we introduce FT-TSTP, a geographic routing protocol capable of delivering messages in an energy-efficient and timely manner to multiple gateways, even in the presence of voids caused by faulty and malicious sensor nodes. At the gateway level, we propose a multi-gateway synchronization protocol, which we call ByzCast, that delivers timely correct data to CPS applications, despite the failure or maliciousness of a number of gateways. We show, through extensive simulations, that our protocols provide better system robustness yielding an increased system and data availability while meeting CPS energy, timeliness, and security demands

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