Castro and Liskov proposed in 1999 a successful solution for byzantine fault-tolerant replication, named PBFT, which overcame performance drawbacks of earlier faulttolerant replication protocols. Other proposals extended PBFT with further optimizations, improving certain conditions. One the key optimizations PBFT-based protocols is use request batching mechanism. If target distributed system dynamic, that is, if its underlying characteristics change dynamically, such as workload, channel...

Some of current Information-centric cellular networks strongly rely on clustering techniques to group users with similar preferences or behavior and assign them a common base station. As result, the most useful contents are kept near users, thereby alleviating backhaul bottlenecks. Despite performance gains, such strategies frequently adopt same replacement policy, irrespectively users' profile. This paper presents simulation-based study that evaluates cache policies through clusters formed...

In order to provide upper-layer applications with continuous message delivery and updated information on membership changes - due process failures, leaves joins -, group communication protocols must exchange messages continuously monitor all members, which in certain load conditions may incur unacceptable overhead the underlying system. Therefore, design of such deal trade-off between performance requirements as speed (e.g., latency) cost overhead). However, when behavior computing...

O estudo objetivou verificar a eficiência, eficácia e confiabilidade de uso do app Violet Wound na detecção bactérias patogênicas em feridas difícil cicatrização. Trata-se um clínico prospectivo realizado uma sala curativo unidade básica saúde. Foram determinados o valor preditivo positivo negativo da fluorescência ciano para Pseudomonas aeruginosa mais seis semanas duração, sensibilidade, acurácia razão verossimilhança utilizando teste diagnóstico acurácia. Para indicador App foi Kappa. Foi...

Os sistemas de reputação se tornam um mecanismo confiança importante à medida em que a Internet torna cada vez mais descentralizada. Todavia, os reputações atuais são construídos sobre infraestruturas centralizadas gerenciamento impactam diretamente na privacidade e própria descentralização da rede. Por outro lado, modelos descentralizados garantem maior escalabilidade elasticidade das aplicações, mas sacrificam prol autenticidade dos participantes. Neste trabalho é proposta Trust over...

This paper explores the potential for improving blockchain performance through implementation of an adaptive consensus machine. Blockchains, as immutable distributed ledgers, have found applications in various domains such cryptocurrency, supply chains, healthcare, and more. The two main types blockchains are permissionless permissioned, each with its own advantages limitations. proposal suggests monitoring transaction metrics on to enable machine adjust operational parameters protocol or...

Replication techniques that tolerate byzantine failures have been applied in distributed computing to cope with hostile environments which system components may fail due malicious or natural causes (e.g., intrusions). From the seminal work of Lamport, Pease and Shostak on Byzantine Generals, 1982, Castro Liskov proposed 1999 a successful solution, named PBFT, overcomes performance drawbacks previous ones, based number protocol optimizations, including use request batching. Such motivated...

Distributed systems are usually modeled by a set of distributed processes spread over number networked computers. Such communicate and synchronize themselves message passing through communication channels. Processes channels can be characterized synchronous or asynchronous timeliness behavior, according to the characteristics underlying (operating system sub-system). Unlike conventional systems, dynamic hybrid may vary time, availability resources occurrence failures. becoming common today...

Distributed systems can be characterized by processes that communicate with each other message passing, through communication channels, and may located at several computers spread over a network. These channels are usually synchronous or asynchronous timeliness behavior, according to the characteristics of underlying system (operating sub-system). Unlike conventional systems, dynamic hybrid distributed vary time, availability resources occurrence failures. Such becoming common today because...

Este trabalho apresenta a blockchain permissionada vCubeChain, que é escalável por definição, sendo baseada na topologia distribuída dinâmica vCube. O vCube um detector de falhas conecta conjunto n processos corretos em uma virtual hierárquica, hipercubo quando todos os estão corretos. Quando falham parada, o se reorganiza mantendo diversas propriedades logarítmicas. A vCubeChain elege líder, utiliza estratégia autonômica difusão confiável para disseminar blocos rede. Cada bloco consiste...

Mobile computing provides new ways to help people in daily routine through ubiquituos, collaborative and social computing. Herein, we combine collaboration with ubiquitous pervasive sensing provide a service that helps on prediting waiting time queues. We argue combining GPS information can improve queue prediction. Our experimental evaluation uses an actual minimarket queue, achieving mean error of 59.56 seconds for predicting queues observed from 120 240 seconds. results show this tool...

Mobile computing provides new ways to help people in daily routine through ubiquituos, collaborative and social computing. Herein, we combine collaboration with ubiquitous pervasive sensing provide a service that helps on prediting waiting time queues. We argue combining GPS information can improve queue prediction. Our experimental evaluation uses an actual minimarket queue, achieving mean error of 59.56 seconds for predicting queues observed from 120 240 seconds. results show this tool...

Mobile computing may improve pervasively user experience through context perception. In this paper, we exercise a prediction service for waiting time on queues using only GPS information and little collaboration ("are you queue?") - combination be used by the vast majority of current mobile phones, once it does not require sophisticated sensing (such as accelerometers other stuff). our proof concept, achieve less than 1 minute predicting error monitoring minimarket queue service. There...

Nuvem computacionais baseadas em infra-estrutura como serviço permitem que recursos sejam alocados sob demanda de forma flexível para atender a necessidades específicas. Desta forma, um datacenter, hospedando diversos nós prover nuvem, pode ter ociosidade com subutilizados consumindo energia elétrica desnecessariamente. Este trabalho propõe implementação uma ferramenta auxilia o gerenciamento energético hosts nuvem implementada na plataforma Openstack -- das mais utilizadas nuvens IaaS--,...

Educational indicators are instruments of significant importance for assessing the outcomes and quality educational institutions. In order to provide information strategic decisions, Business Intelligence systems gaining more space in Information Technology market. This article intends identify main their various approaches, evaluate contributions and/or inadequacies pedagogical management Instituto Federal da Bahia, besides addressing theme, identifying origin, concepts applicability....

A complex web of relationships provides goods for manufacturing, assembling, and delivering final products known as the supply chain. Emerging technologies have been used in chain systems order to provide traceability. However, these tend be centralized, monopolistic, asymmetric. As a consequence, they may result trusting problems, such fraud, corruption, tampering. Blockchain technology new approach information based on decentralization, that can apply systems. This work presents...

Manter ambientes de computação em nuvem sempre disponíveis e cumprindo os níveis mínimos serviço é uma tarefa que exige um gerenciamento eficiente dos recursos computacionais. Prever cargas trabalho computacionais estratégia pode trazer ganhos ao possibilitar a tomada ações proativas no uso recursos, entanto, fazer tais predições heterogêneos dinâmicos desafio. Neste sentido, este demonstra aplicação técnicas para predizer valores séries temporais utilizando modelos ARIMA Redes Neurais...