Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
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Item Availability and operability in optical transport network architectures(IEEE, 2020-08) Gomba, Masimba; Nleya, Bakhe; Chidzonga, Richard F.A typical optical transport network interconnects multitudes of offices. With the advent of the Internet of Things (IoT) networking approach, it has become necessary for such transport structures to be flexible enough to accommodate heterogeneous communication services that generate escalating traffic loads every time. It is also key not only to accommodating continuously escalating traffic levels, but also to maintain a consistent Quality of Service, operability as well availability. This can only be achieved through the provisioning of effective and dynamic network control. In this paper, we explore the various operational issues such as incompatibilities in terms of physical layer transmission requirements and other control and management challenges emerging in present and future/ (envisaged) optical transport networks.Item Perspectives on impact of high penetration of renewable sources on LV networks(IEEE, 2020-08) Chidzonga, Richard F.; Nleya, BakheIn most countries, electricity power grids have not undergone extensive modernization and/or liberalization. They are still predominantly vertically integrated i.e. designed and opera ted top (Generation)-down (Distri bution/loads). Increasing electricity demand and rising costs are ca using congestion and strain on power distribution networks cperartens. Fossil fuels are in decline and blamed for most negative environmental l and cUmadc imp acts on world economics and societal maleficence. Through out the world they are heightened impetuses to migrate to cleaner Renewable Energy (RE) sources and incorporate more intelligence in the utilization of energy. This has birthed the concept of smart grids with high participation of various clean energy sources . Hybrid renewable energy generation (HRE) systems are complementary technologies that have potential to mitigate climatic variability effects which are still a challenge with respect to dispatchability of RE resources. The emerging smart power grids are no longer unidirectional in terms of energy Row, but also allow users to inject energy back into the grids. The bi-directional now of energy has a significant positive impact on overall systems design and operation. This article provides an overview of the preliminary work that done to assess impact scenarios on power grids with increased penetration of RE. Simulation results show possible negative factors that may affect QoS parameters of typical LV power networks.Item Evaluation of wavelength congestion in transparent optical transport networks(IEEE, 2020-08) Gomba, Ndadzibaya Masimba; Nleya, Bakhe; Mutsvangwa, Andrew; Chidzonga, Richard F.Transparent Optical networks are generally regarded as a possible solution for the provisioning of ultrahigh speed transmission and switching capabilities to accommodate bandwidth hungry applications and services. Most of such applications and services involve streaming of high-definition video. However, since al source and destination pair establishments within a given Transparent optical transport network are assumed to be within optical signal reach, such networks do not incorporate regenerators. The lack of regenerators often leads to a serious degradation of the signal to noise ratio as a result of the effects of physical layer impairments accumulated as it traverses the network. This motivates us to propose and present a Q-factor tool that takes into account the various physical layer impairments. The proposed tool’s efficacy is evaluated by way of simulation.Item A bursts contention avoidance scheme based on streamline effect awareness and limited intermediate node buffering in the core network(Blue Eyes Intelligence Engineering and Sciences Publication, 2020-08-30) Nleya, Bakhe; Chidzonga, Richard F.In an Optical Burst Switched (OBS) network, data packets sourced from peripheral networks are assembled into huge sized data bursts. For each assembled data burst, an associated control signal in the form of a burst control packet is (BCP) is gen-erated and scheduled at an offset time ahead of the data burst. The offset timing is to allow for the pre-configuration of required re-sources at all subsequent intermediate nodes prior to the actual data burst’s arrival. In that way, the data burst will fly-by each node and hence no requirement for temporary buffering at all in-termediate nodes. An operational requirement of an OBS network is that it be loss-less as in that way a consistent as well as acceptable quality of service (QoS) for all applications and services it serves as a platform can be guaranteed. Losses in such a network are mainly caused by improper provisioning as well as dimensioning of re-sources thus leading to contentions among bursts and consequently discarding of some of the contending data bursts. Key to both pro-visioning as well as proper dimensioning of the available resources in an optimized way is the implementation of effective routing and wavelength (RWA) that will seclude any data losses due to conten-tion occurrences. On the basis of the effects of the streamline effect (SLE), that is, effectively secluding primary contention among flows (streams) in the network, we propose in this paper a limited intermediate buffering that couples with SLE aware prioritized RWA (LIB-PRWA) scheme that combats secondary contention as well. The scheme makes routing decisions such as selection of pri-mary and deflection routes based on current resources states in the candidate paths. A performance comparison of the proposed scheme is carried out and simulation results demonstrate its com-parative abilities to effectively reduce losses as well as maintaining both high network resources utilization as well as QoS.Item A review of IoT enabled networks' architecture and access control(Ponte Academic Journal, 2020-01) Bopape, Lebogang P.; Nleya, Bakhe; Chidzonga, Richard F.Current IP and other networks such as Power Smart Grids are fast evolving, thus resulting in diverse connectivity challenges. This has led to the emergence of "the Internet of Things” (IoT) network transforming the legacy networks towards Device-to-Device (D-2-D) communication standards. By 2022, IoT will seamlessly interconnect the globe via intelligent devices and sensors of varying types and in the process large volumes of data will be generated. The resultant network structure will benefit mankind by helping in making complex decisions. In this paper, we overview both IoT enabled network architecture as well as and access and control framework for various services and applications. We commence with a review of a generalized IoT enabled network's security architecture as well as how the various elements constituting them interact. The paper then describes an access control framework applicable to the various would be applications and services.Item Energy optimization for a smart prosumer(PONTE International Scientific Researches Journal, 2020-04) Chidzonga, Richard F.; Nleya, BakheThis paper outlines the optimization of cost of electrical energy consumption for a small microgrid typical of a residential area where each household has renewable generation capability and the daily load is portioned into essential none-interruptible and schedulable or interruptible loads. Dual tariffs exist, for buying and the other for in-feed into the utility grid. The optimization makes appliances scheduling decisions to suit prevailing power availability as well amount of power to sell or procure from the utility depending on availability and prevailing real time pricing. We assume availability of time-variant energy parameters, then formulate a global optimization problem whose solutions leads to quantification of the optimal amount of energy purchased and sold for each of the individual households. When the unrealistic assumption of availability of information is removed from the implementation of the global optimization, an online algorithm that only requires the current values of the time varying supply and demand processes shows by simulation that the distributed algorithm can realise credible scheduling of prosumer household electricity usage. This is imperative as the very requirement of involving the consumer for appliances scheduling defeats the optimization cause as humans are not suitable for such repetitive and mundane tasks.