Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
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Item Intercloud resource discovery using Blockchain(Institute of Electrical and Electronics Engineers (IEEE), 2021) Sharma, Mekhla; Singh, Jaiteg; Gupta, Ankur; Tanwar, Sudeep; Sharma, Gulshan; Davidson, I. E.The intercloud represents a logical evolution of cloud computing that extends its computational scale and geographic footprint by collaborating with disparate cloud service providers (CSPs) for resource sharing. Discovering resources belonging to heterogeneous CSPs is not only the primary but critical operation for the intercloud. However, achieving resource discovery in a deterministic manner within this global distributed environment is non-trivial. The literature has proposed several resource discovery approaches for the federated intercloud based on trusted and centralized thirdparty entities. Few approaches, however, exist for the non-federated intercloud, which by definition has no central entity to enable the resource discovery process. Some P2P-based resource discovery techniques have been proposed by researchers, industry players and standardization bodies like Global InterCloud Technology Forum (GICTF). However, existing P2P-based approaches in the non-federated intercloud do not adequately address authentication, non-repudiation of resource information, secure storage and management of transactional records, management of trust/reputation and optimal resource selection and provisioning. This research paper presents BIRD, a Blockchain-based Intercloud Resource Discovery framework that involves participating CSPs connected in a P2P network using blockchain to manage resource information and maintain transactional records. The BIRD framework alleviates the requirement of a trusted third party for discovering and managing resources. The main features involved in the BIRD framework are i) latency optimization, ii) fine-grained control mechanism, and iii) Quality-of Service, Trust and Reputation (QTR) indices. Latency optimization achieves faster resource discovery, fine-grained control mechanism for intercloud resource discovery, and QTR is for quality CSP or resource selection. BIRD uses blockchain to maintain transactions between CSPs securely.Item MVDC railway traction power systems, state-of-the art, opportunities, and challenges(MDPI AG, 2021) Simiyu, Patrobers; Davidson, I. E.Advances in voltage-source converters (VSCs), as well as their successful application in VSC-HVDC systems, have motivated growing interests and research in medium-voltage direct current (MVDC) traction power systems (TPSs) for high-speed rail (HSR) applications. As an emerging power-converter-based infrastructure, this study reviewed developments that shape two key evolving pieces of equipment—namely, high-power traction substation (TSS) converters, and power electronic transformers (PETs)—for MVDC TPS as well as prospects for smart grid (SG) applications in the future. It can be deduced that cost-effective and robust high-power TSS converters are available from hybrid modular multilevel converters (MMCs) for enhanced performance and fault-tolerance capability. In addition, silicon carbide (SiC) MMC-based PETs with input-series-output-parallel (ISOP) configuration are present for greater weight/size reduction and efficiency for MVDC rolling stock design. Finally, the implementation of a smart MVDC TPS incorporating a sophisticated railway energy management system (REM-S) based on the smart grid principles is feasible in the future, with numerous benefits. However, there are related challenges, like knowledge gaps on these technologies, the high costs involved, and lack of standardization to overcome to realize widespread future commercial deployment.