Sally McClean - Academia.edu (original) (raw)

Papers by Sally McClean

Live Migration (LM) of Virtual Machine (VM) is a process of transferring a working VM from on hos... more Live Migration (LM) of Virtual Machine (VM) is a process of transferring a working VM from on host to another host of a different physical machine without interfering the VM. In datacentre networks, LM enables flexibility in resource optimisation, fault tolerance and load balancing. However, in real time, the resource consumption and latency of live VM migration reduce these benefits to much less than their potential. In this paper, we present the results of an experimental study that evaluates LM in our unique high speed optical fibre network connecting Northern Ireland, Dublin and Halifax (Canada). We observe that using Pre-Copy LM extra large amounts of stressed memory leads to non convergence over high latency paths. However, using Post-copy LM the total migration time as well as downtime is dominated by specific memory utilisation patterns inside the virtualised guest. We experience variation in total migration time and downtime using Post-Copy LM considering Quality of Service (QoS) parameters, which can have significant impact in the cloud applications performance.

Ubiquitous Computing and Ambient Intelligence, 2016

In this paper we study the use of medical history information extracted from the Utah Population ... more In this paper we study the use of medical history information extracted from the Utah Population Database (UPDB) to predict adoption of a reminder solution for people with dementia. The adoption model was built using 24 categorised features. The kNN classification algorithm gave the best performance with 85.8 % accuracy. Whilst data from the UPDB is more readily available than that in our previous work, the results highlight the benefit of including psychosocial and background information within an adoption model.

International journal on advances in intelligent systems, 2018

The IT industry has been revolutionized in the past few decades. Cloud Computing companies (Googl... more The IT industry has been revolutionized in the past few decades. Cloud Computing companies (Google, Yahoo, Gaikai, ONLIVE, Amazon and eBay) use large data centers which are comprised of virtual computers that are placed globally and require a lot of power cost to maintain. Demand for energy consumption is increasing day by day in IT firms. Therefore, Cloud Computing companies face challenges towards the maintenance of power costs. Energy consumption is dependent upon several factors, e.g., service level agreement, virtual machine selection techniques, optimization policies, workload types etc. We address a solution for the energy saving problem by enabling dynamic voltage and frequency scaling technique for gaming data centers. The dynamic voltage and frequency scaling technique is compared against non-power aware and static threshold detection techniques. This helps service providers to meet the quality of service and quality of experience constraints by meeting service level agree...

With the rise in popularity of cloud computing the amount of energy consumed by the cloud computi... more With the rise in popularity of cloud computing the amount of energy consumed by the cloud computing data centres has increased dramatically. Cloud service providers are aiming to reduce their carbon footprint by reducing the energy their data centres produce, while maintain an expected Quality-of-Service adhering to set Service Level Agreements. In this paper, we present our suggested approach for using previously researched energy efficiency techniques, particularly Dynamic Voltage/Frequency Scaling and sleep states, more efficiently through the aid of an SLA-based priority scheduling algorithm, and the results we expect from our research.

Open J. Internet Things, 2015

Wireless sensor networks have increasingly become contributors of very large amounts of data. The... more Wireless sensor networks have increasingly become contributors of very large amounts of data. The recent deployment of wireless sensor networks in Smart City infrastructures have led to very large amounts of data being generated each day across a variety of domains, with applications including environmental monitoring, healthcare monitoring and transport monitoring. The information generated through the wireless sensor nodes has made possible the visualization of a Smart City environment for better living. The Smart City offers intelligent infrastructure and cogitative environment for the elderly and other people living in the Smart society. Different types of sensors are present that help in monitoring inhabitants’ behaviour and their interaction with real world objects. To take advantage of the increasing amounts of data, there is a need for new methods and techniques for effective data management and analysis, to generate information that can assist in managing the resources inte...

Journal of Computer and Communications, 2019

Cluster Computing, 2019

In recent years, lot of research has been carried in the field of cloud computing and distributed... more In recent years, lot of research has been carried in the field of cloud computing and distributed systems to investigate and understand their performance. Economic impact of energy consumption is of major concern for major companies. Cloud Computing companies (Google, Yahoo, Gaikai, ONLIVE, Amazon and eBay) use large data centers which are comprised of virtual computers that are placed globally and require a lot of power cost to maintain. Demand for energy consumption is increasing day by day in IT firms. Therefore, Cloud Computing companies face challenges towards the economic impact in terms of power costs. Energy consumption is dependent upon several factors, e.g., service level agreement, virtual machine selection techniques, optimization policies, workload types etc. We address a solution for the energy saving problem by enabling dynamic voltage and frequency scaling technique for gaming data centers. The dynamic voltage and frequency scaling technique is compared against non-power aware and static threshold detection techniques. This helps service providers to meet the quality of service and quality of experience constraints by meeting service level agreements. The CloudSim platform is used for implementation of the scenario in which game traces are used as a workload for testing the technique. Selection of better techniques can help gaming servers to save energy cost and maintain a better quality of service for users placed globally. The novelty of the work provides an opportunity to investigate which technique behaves better, i.e., dynamic, static or non-power aware. The results demonstrate that less energy is consumed by implementing a dynamic voltage and frequency approach in comparison with static threshold consolidation or non-power aware technique. Therefore, more economical quality of services could be provided to the end users.

Journal of biomedical informatics, Oct 29, 2016

Assistive technologies have been identified as a potential solution for the provision of elderly ... more Assistive technologies have been identified as a potential solution for the provision of elderly care. Such technologies have in general the capacity to enhance the quality of life and increase the level of independence among their users. Nevertheless, the acceptance of these technologies is crucial to their success. Generally speaking, the elderly are not well-disposed to technologies and have limited experience; these factors contribute towards limiting the widespread acceptance of technology. It is therefore important to evaluate the potential success of technologies prior to their deployment. The research described in this paper builds upon our previous work on modeling adoption of assistive technology, in the form of cognitive prosthetics such as reminder apps and aims at identifying a refined sub-set of features which offer improved accuracy in predicting technology adoption. Consequently, in this paper, an adoption model is built using a set of features extracted from a user&...

International Journal of Computers Communications & Control, 2006

The world of telecommunications continues to provide radical technologies. Offering the benefits ... more The world of telecommunications continues to provide radical technologies. Offering the benefits of a superior television experience at reduced long-term costs, IPTV is the newest offering. Deployments, however, are slow to be rolled out; the hardware and software support necessary is not uniformly available. This paper examines the challenges in providing IPTV services and the limitations in developments to overcome these challenges. Subsequently, a proposal is made which attempts to help solve the challenge of fulfilling real-time multimedia transmissions through provisioning for differentiated services. Initial implementations in Opnet are documented, and the paper concludes with an outline of future work.

Optical and wireless technology integration schemes merge the high-speed and high-capacity of the... more Optical and wireless technology integration schemes merge the high-speed and high-capacity of the optical networks with the low-cost, wide-coverage and mobility features of wireless counterparts for Subscriber Stations (SSs). It is also financially viable for the telecommunication service providers particularly in rural areas. In order to successfully integrate the two technologies, there are some technical concerns in terms of Architectural aspects, Physical Layer features and Media Access Control (MAC) related issues. This paper is mainly focused on the analysis of the key topics in MAC-related issues over the converged scenario and proposes an Inter-channel and Intrachannel Dynamic Wavelength/Bandwidth Allocation (IIDWBA) algorithm where the hybrid Passive Optical Network (PON) acts as a backhaul technology for the wireless counterpart. Performance of the proposed algorithm is evaluated through conducted simulation scenarios in terms of different Quality of Service (QoS) metrics where the IIDWBA algorithm shows a better performance when it is compared with the scenario in which it has not been employed.

Data centre energy costs are reduced when virtualisation is used as opposed to physical resource ... more Data centre energy costs are reduced when virtualisation is used as opposed to physical resource deployment to a volume sufficient to accommodate all application requests. Nonetheless, regardless of the resource provisioning approach, opportunities remain in the way in which they are made available and workload is scheduled. Cost incurred at a server is a function of its hardware characteristics. The objective of our approach is therefore to pack workload into servers, selected as a function of their cost to operate, to achieve (or as close to) the maximum recommended utilisation in a cost-efficient manner, avoiding instances where devices are under-utilised and management cost is incurred inefficiently. This is based on queuing theory principles and the relationship between packet arrival rate, service rate and response time, and recognises a similar exponential relationship between power cost and server utilisation to drive its intelligent selection for improved efficiency. There is a subsequent opportunity to power redundant devices off to exploit power savings through avoiding their management.

Proceedings of the 3rd International ICST Conference on Simulation Tools and Techniques, 2012

Ability to quantify carbon cost C 1 emitted from the network, which is a function of traffic volu... more Ability to quantify carbon cost C 1 emitted from the network, which is a function of traffic volume T, queuing delay Q, bandwidth availability B, bit error rate ER and packet loss ratio R on the path: Ability to enforce dynamic network management (during which energy awareness drives energy efficiency), with an aim to achieve a carbon cost C 2, where C 2 <C 1 .

Hybrid optical and wireless technology integrations have been considered as one of the most promi... more Hybrid optical and wireless technology integrations have been considered as one of the most promising candidates for the next generation broadband access networks for quite some time. The integration scheme provides the bandwidth advantages of the optical networks and mobility features of the wireless networks for Subscriber Stations (SSs). It also brings economic efficiency to the network providers particularly in rural area where the existing wired telecommunication infrastructures such as Digital Subscriber Line (DSL), Cable Modem (CM), T-l/E-I networks or fibre deployments are either costly or unreachable. For successful integration of the optical and wireless technologies there are some technical issues which need to be addressed efficiently in order to provide End-to-End (ETE) and diverse Quality of Service (QoS) for various service classes. This paper investigates the possible challenging issues for the integrated structure of the Time Division Multiplexing and Wavelength Division Multiplexing Ethernet Passive Optical Networks (TDM EPON and WDM EPON) with the Worldwide Interoperability for Microwave Access and Wireless Fidelity (WiMAX and Wi-Fi) networks. To reduce the ETE delay and provide the QoS for diverse service classes, we have compared six existing upstream scheduling mechanisms in two levels which are distributed on Access Points (APs) from Wi-Fi domain and Base Stations (BSs) from WiMAX domain. Performance evaluations of the existing scheduling techniques for three popular service classes (Quad-play) have been studied which show the strong impact of using the efficient up-link scheduler in converged scenario. We have also proposed a dynamic scheduling algorithm for optical and wireless integration scheme, which is under the implementation and evaluation process.

2012 Second Symposium on Network Cloud Computing and Applications, 2012

Clouds and data centres are significant consumers of power. There are however, opportunities for ... more Clouds and data centres are significant consumers of power. There are however, opportunities for optimising carbon cost here as resource redundancy is provisioned extensively. Data centre resources, and subsequently clouds which support them, are traditionally organised into tiers; switch-off activity when managing redundant resources therefore occurs in an approach which exploits cost advantages associated with closing down entire network portions. We suggest however, an alternative approach to optimise cloud operation while maintaining application QoS: Simulation experiments identify that network operation can be optimised by selecting servers which process traffic at a rate that more closely matches the packet arrival rate, and resources which provision excessive capacity additional to that required may be powered off for improved efficiency. This recognises that there is a point in server speed at which performance is optimised, and operation which is greater than or less than this rate will not achieve optimisation. A series of policies have been defined in this work for integration into cloud management procedures; performance results from their implementation and evaluation in simulation show improved efficiency by selecting servers based on these relationships.

2011 IEEE 4th International Conference on Cloud Computing, 2011

Resource allocation in the cloud is usually driven by performance predictions, such as estimates ... more Resource allocation in the cloud is usually driven by performance predictions, such as estimates of the future incoming load to the servers or of the quality-of-service (QoS) offered by applications to end users. In this context, characterizing web workload fluctuations in an accurate way is fundamental to understand how to provision cloud resources under time-varying traffic intensities. In this paper, we investigate the Markovian Arrival Processes (MAP) and the related MAP/MAP/1 queueing model as a tool for performance prediction of servers deployed in the cloud. MAPs are a special class of Markov models used as a compact description of the time-varying characteristics of workloads. In addition, MAPs can fit heavy-tail distributions, that are common in HTTP traffic, and can be easily integrated within analytical queueing models to efficiently predict system performance without simulating. By comparison with tracedriven simulation, we observe that existing techniques for MAP parameterization from HTTP log files often lead to inaccurate performance predictions. We then define a maximum likelihood method for fitting MAP parameters based on data commonly available in Apache log files, and a new technique to cope with batch arrivals, which are notoriously difficult to model accurately. Numerical experiments demonstrate the accuracy of our approach for performance prediction of web systems.

Optical Switching and Networking, 2013

Optical and wireless technology integration has been proposed as one of the most promising nomine... more Optical and wireless technology integration has been proposed as one of the most promising nominees for the nextgeneration broadband access networks for quite some time. Integration scheme merges the high-speed and high-capacity of the optical networks with the low-cost, wide-coverage and mobility features of the wireless counterparts for the Subscriber Stations (SSs). It is also financially viable for the telecommunication service providers, particularly in the rural area where the development of optical infrastructure or expansion of the existing telecommunication solutions such as Digital Subscriber Line (DSL), Cable Modem (CM) or T-1/E-1 networks are either too costly or unreachable. In order to successfully integrate the two technologies, there are some technical concerns in terms of Architectural aspects, Physical Layer features and Media Access Control (MAC) related issues, which need to be addressed efficiency and efficiently in order to provide the smooth end-to-end (e2e) integration. This paper is mainly focused upon the analysis of the key topics in MACrelated issues such as E2E wavelength/bandwidth requests and allocations over the converged scenario. It proposes an Interchannel and Intra-channel Dynamic Wavelength/Bandwidth Allocation (IIDWBA) algorithm where the hybrid Passive Optical Network (PON) acts as a back haul technology for the wireless counterpart. The proposed algorithm works in three phases, namely, Initialisation, Intra-channel bandwidth allocations and Inter-channel bandwidth allocations and is capable of allocating wavelength/bandwidth efficiently and effectively over the converged scenario. Performance of the proposed algorithm is evaluated through conducted simulation scenarios under different simulation parameters, traffic patterns and load values. According to the captured results, IIDWBA algorithm shows a better performance when it is compared to the scenario in which it has not been employed.

Health Care Management Science, 2009

Healthcare resource planners need to develop policies that ensure optimal allocation of scarce he... more Healthcare resource planners need to develop policies that ensure optimal allocation of scarce healthcare resources. This goal can be achieved by forecasting daily resource requirements for a given admission policy. If resources are limited, admission should be scheduled according to the resource availability. Such resource availability or demand can change with time. We here model patient flow through the care system as a discrete time Markov chain. In order to have a more realistic representation, a nonhomogeneous model is developed which incorporates timedependent covariates, namely a patient's present age and the present calendar year. The model presented in this paper can be used for admission scheduling, resource requirement forecasting and resource allocation, so as to satisfy the demand or resource constraints or to meet the expansion or contraction plans in a hospital and community based integrated care system. Such a model can be used with both fixed and variable numbers of admissions per day and should prove to be a useful tool for care managers and policy makers who require to make strategic management decisions. We also describe an application of the model to an elderly care system, using a historical dataset from the geriatric department of a London hospital.