Smart PIN: utility-based replication and delivery of multimedia content to mobile users in wireless networks

Next generation wireless networks rely on heterogeneous connectivity technologies to support various rich media services such as personal information storage, file sharing and multimedia streaming. Due to users’ mobility and dynamic characteristics of wireless networks, data availability in collaborating devices is a critical issue. In this context Smart PIN was proposed as a personal information network which focuses on performance of delivery and cost efficiency. Smart PIN uses a novel data replication scheme based on individual and overall system utility to best balance the requirements for static data and multimedia content delivery with variable device availability due to user mobility. Simulations show improved results in comparison with other general purpose data replication schemes in terms of data availability

Efficient data reliability management of cloud storage systems for big data applications

Cloud service providers are consistently striving to provide efficient and reliable service, to their client's Big Data storage need. Replication is a simple and flexible method to ensure reliability and availability of data. However, it is not an efficient solution for Big Data since it always scales in terabytes and petabytes. Hence erasure coding is gaining traction despite its shortcomings. Deploying erasure coding in cloud storage confronts several challenges like encoding/decoding complexity, load balancing, exponential resource consumption due to data repair and read latency. This thesis has addressed many challenges among them. Even though data durability and availability should not be compromised for any reason, client's requirements on read performance (access latency) may vary with the nature of data and its access pattern behaviour. Access latency is one of the important metrics and latency acceptance range can be recorded in the client's SLA. Several proactive recovery methods, for erasure codes are proposed in this research, to reduce resource consumption due to recovery. Also, a novel cache based solution is proposed to mitigate the access latency issue of erasure coding

A Byzantine Fault-Tolerant Ordering Service for the Hyperledger Fabric Blockchain Platform

Hyperledger Fabric (HLF) is a flexible permissioned blockchain platform designed for business applications beyond the basic digital coin addressed by Bitcoin and other existing networks. A key property of HLF is its extensibility, and in particular the support for multiple ordering services for building the blockchain. Nonetheless, the version 1.0 was launched in early 2017 without an implementation of a Byzantine fault-tolerant (BFT) ordering service. To overcome this limitation, we designed, implemented, and evaluated a BFT ordering service for HLF on top of the BFT-SMaRt state machine replication/consensus library, implementing also optimizations for wide-area deployment. Our results show that HLF with our ordering service can achieve up to ten thousand transactions per second and write a transaction irrevocably in the blockchain in half a second, even with peers spread in different continents

Internet-scale storage systems under churn - a study of the steady state using markov models

Markov model

Target costing in construction: a comparative study

Target costing is an approach for the development of new products in the automobile industry, aimed at reducing their life-cycle costs while ensuring quality, reliability and other client requirements, by examining all possible ideas for cost reduction at the product planning, research and development and prototyping phases. Prior studies have attempted to adapt the manufacturing target costing process to the project-based nature of the construction industry. This paper aims to provide insights for future target costing implementations in the public sector projects. A qualitative comparison of three studies is performed through the lens of a set of target costing influencing factors. Similarities and differences revealed in the comparison suggest that factors related to supplier-base strategy and to the nature of customer are potentially relevant to future target costing implementations in public sector projects

What do we know about Immunity to SARS-CoV-2? Implications for Public Health Policies

Additional support from ISGlobal’s Antoni Plasència and Josep M. AntóAs the COVID-19 pandemic progresses, so does our knowledge of the magnitude, type and durability of the immune response to SARS-CoV-2 as a result of natural infection or vaccination. This information is crucial since it will largely define the strategies we need to implement in order to protect individuals and populations. With this in mind, the GCMSC presents its second report, where they review the current knowledge on immunity to SARS-CoV-2 and the implications in terms of public health policies