With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Sensor networks comprise of a collection of resource-constrained, low cost, sometimes fragile wireless motes which have the capability to gather information about their surroundings through the use of sensors, and can be conceived as a distributed computing platform for applications ranging from event detection to environmental monitoring. A Sensor Network Query Processor (SNQP) is a means of collecting data from sensor networks where the requirements are defined using a declarative query language with a set of Quality of Service (QoS) expectations. As sensor networks are often deployed in hostile environments, there is a high possibility that the motes could break or that the communication links between the motes become unreliable. SNQP Query Execution Plans (QEPs) are often optimised for a specific network deployment and are designed to be as energy efficient as possible whilst ensuring the QEPs meet the QoS expectations, yet little has been done for handling the situation where the deployment itself has changed since the optimisation in such a way as to make the original QEP no longer efficient, or unable to operate. In this respect, the previous work on SNQPs has not aimed at being resilient to failures in the assumptions used at compilation/optimisation time which result in a QEP terminating earlier than expected. This dissertation presents a collection of approaches that embed resilience into a SNQP generated QEPs in such a way that a QEP operates for longer whilst still meeting the QoS expectations demanded of it, thereby resulting in a more reliable platform that can be applicable to a broader range of applications. The research contributions reported here include (a) a strategy designed to adapt to predictable node failures due to energy depletion; (b) a collection of strategies designed to adapt to unpredictable node failures; (c) a strategy designed to handle unreliable communication channels; and (d) an empirical evaluation to show the benefits of a resilient SNQP in relation to a representative non-resilient SNQP.

Dissertation (MArch(Prof))--University of Pretoria, 2014. / Architecture / MArch(Prof) / Unrestricted

Thesis (MTech (Business Administration))--Cape Peninsula University of Technology, 2020 / The research was focused on business continuity management as a key discipline towards building a resilient Western Cape Government. It provided an opportunity to identify existing business continuity processes to determine the level of preparedness of the Western Cape Government to ensure continued business due to a disruption. The inability of the public sector to manage and facilitate sound business continuity processes in anticipation of disruptive events have placed it in a position where it would be unable to deliver services to citizens and stakeholders. As the current business environment was continuously evolving, Government as an organization was therefore not immune to change and disruption, whether generated internally or externally. For government to be resilient it required the holistic management of risk but also the ability to adapt and respond to change with a limited impact on the delivery of services. Business Continuity was the core to building and improving organizational resilience. It had been a proven methodology that organizations should embrace as part of a holistic approach to the management of risks and threats. Legislation and/or policies have been drafted for the public sector to guide with the management of risks. As an organ of state and part of the public sector the Western Cape Government was therefore obliged to manage risks in a way that ensured that government was able to continue to render a service both internally and externally with as little impact as possible. Business continuity management identified the priorities of an organization as well as prepared solutions to address disruptive threats. The aim of the study was the exploration of the state of business continuity within the Western Cape Government. The objectives of the study were to: Identify current business continuity processes; Evaluate current business continuity processes; Critically analyse existing business continuity documentation; and Identify the links between business continuity and resilience. The research questions were focused on getting departments to express how business continuity was facilitated; clarity in respect of processes; input source of business continuity documentation; as well as determining whether departments acknowledged the benefits of having business continuity management towards building a resilient Western Cape Government. Previous work reinforced the importance of having sound business continuity processes in place. From the literature it would appear that business continuity in the public sector was fairly new and developmental in nature. Previous work also recognized that each and every organization was unique and as such the process should be aligned with the core functions and/or mandates afforded by legislation and/or policies. The research approach deemed most appropriate for this particular study was the Interpretivist approach. Not only was this approach value laden but it allowed for the exploration of the theory and obtaining of rich in-depth data from the participants. It also allowed for the contextualization of the problem as it related to the business continuity processes within the Western Cape Government. The research method was qualitative using interviews and document analysis as the most suited research instruments to elicit qualitative data required to render the research process as valid. It was concluded that having sound business continuity processes in place would greatly support organizations with the management of disruptions. Business continuity should be a proactive plan to avoid and mitigate risk associated with disruption of operations and needed to be managed in a way that objectives were met. Further to this it should be noted that the resilience maturity of the Western Cape Government remained reactive and concerted efforts towards becoming proactive should be considered.

Compacted soils are frequently used as subgrade for pavements as well as commercial and residential buildings. The stiffness and shear strength properties of compacted soils, which are collectively denoted as Ω in this thesis, fluctuate with moisture content changes that result from the influence of environmental factors such as the evaporation and infiltration. For example, mechanistic pavement design methods require the information of resilient modulus (MR), which is the soil stiffness behavior under cyclic traffic loading, and its variation with respect to the soil moisture content determined from laboratory tests or estimation methods. Significant advances have been made during the last five decades to understand and model the variation of the Ω with respect to soil moisture content and soil suction (s) based on the principles of mechanics of unsaturated soils. There are a variety of models presently available in the literature relating the Ω to the s using different approaches. There are however uncertainties extending these models for predicting Ω - s relationships when they are used for a larger soil suction range. In addition, the good performance of these models are only valid for certain soil types for which they were developed and calibrated. Studies presented in this thesis are directed towards developing a unified methodology for modelling the relationship between the Ω and the s using limited while easy-to-obtain information. However, more emphasis has been focused on the MR - s relationships of pavement subgrade soils considering the need for the application of the mechanistic pavement design methods in Canada. The following studies have been conducted: (i) State-of-the-art review on existing equations in the literature for the MR - s relationships is summarized. A comparison study is followed to discuss the strengths and limitations of these equations; (ii) A unified methodology for modelling the Ω - s relationships is proposed. Experimental data on 25 different soils are used to verify the proposed unified methodology. The investigations are applied on small strain shear modulus, elastic modulus, and peak and critical shear strength. Good predictions are achieved for all of the investigated soils; (iii) Performance of the proposed methodology is examined for the MR - s relationships using experimental data of 11 subgrade soils. Reasonably good predictions are achieved for all of the subgrade soils; (iv) Extensive experimental investigations are conducted on the MR - s relationships for several subgrade soils collected from various regions in Canada. Experimental results suggest non-linear variation in the MR with respect to s, moisture content and the external stress. The measured results are modelled using the proposed methodology with adequate success; (v) Additional experimental investigations are performed to determine the variation of the elastic modulus (E) and unconfined compression strength (qu) with the s and the gravimetric moisture content (w) for several Canadian subgrade soils. An approach, which is developed extending the proposed unified methodology, is used to normalize the measured MR - w, E - w and qu - w relationships. It is shown that the normalized MR - w, E - w and qu - w relationships exhibit remarkable similarity and can be well described using the proposed approach. Such similarity in the normalized Ω - moisture content relationships are also corroborated using the experimental data on several other soils reported in the literature. The proposed unified methodology alleviates the need for the determination of the Ω - s relationships which requires elaborate testing equipment that needs the supervision of trained personnel and is also time-consuming and expensive. In addition, experimental programs in this thesis provide detailed experimental data on the MR, E, qu, and soil-water characteristic curves of Canadian subgrade soils. These data will be helpful for the better understanding of the hydro-mechanical behavior of the Canadian subgrade soils and for the implementation of the mechanistic pavement design method in Canada. The simple tools presented in this thesis are promising and encouraging for implementing the mechanics of unsaturated soils into conventional geotechnical engineering practice.

Companies must be flexible and adaptable to compete in today's market. Those with such skills can better meet changing customer needs. Customization can add value by meeting customers' specific needs. Engineer-to-order (ETO) is used as a strategy to meet customer needs. High-mix, low-volume products are promoted. This creates uncertainty about the demand that the organization needs to deal with in a fast and efficient way, which results in applying agile as an approach to dealing with uncertainty. In addition, the organization needs to be more resilient to the vulnerability to which the market exposes the organization. However, at the same time, the organization needs the ability to make sense of the state of its environment, detect new threats, adopt new technologies and organizational attributes, and contribute to its resilience. However, it is unclear how to simultaneously develop an agile-based manufacturing strategy and a more resilient organization. Evidently, research is limited regarding the management of both the ability to move quickly and easily (Agile) and the organization's capacity to rapidly adapt to and respond to all types of risks (Resilience) within complex ETO organizations. In light of this, the purpose of this study is to investigate how agile and resilient practices can be implemented in ETO organizations to facilitate the production of complex or specialized products, as well as the capacity to absorb stress, recover essential functionality, and thrive under altered conditions. This study has primarily adopted a qualitative methodology, which uses both a case study approach and a literature review. The case study is based on interviews, a document study, and questionaries. The result from this study presents critical areas to improve from the point of view of agile and resilient practices so that the organization can have better performance and productivity. Improving areas such as communication, management style, the development of a model and knowledge management, the desired organizational structure, and the customer's role is essential in order to increase the organization's efficiency and decrease its uncertainty and risks.

<p>The resilient modulus and Poisson's ratio of granular materials used in flexible pavement structures is highly nonlinear, stress/strain path and direction-dependent. Resilient properties are very important for realistic flexible pavement design. By far, several important aspects, such as the effect of stress path, major principal stress rotation, initial stress state and inherent fabric, on the cross-anisotropic resilient properties are not fully understood. The main objective of this thesis was to study the cross-anisotropic resilient properties of granular materials along various stress paths from both initial isotropic and initial anisotropic stress states. Extensive resilient modulus stress path tests were performed for this purpose. </p> <p> In this research, the resilient behaviour of the test material for initial isotropic stress states along various stress paths was investigated first, with particular interest in the stress/strain path dependency. New resilient modulus equations were then developed, by taking into account the effect of confining pressure and resilient strains. These equations can be used to estimate the cross-anisotropic resilient modulus corresponding to initial isotropic stress states. Selection of Poisson's ratio was also investigated. </P> <p> The effect of initial stress state on the resilient responses was studied through a series of stress path tests with constant confining pressure and constant vertical stress, respectively. Based on the experimental findings, revised equations for resilient modulus and Poisson's ratio were proposed to account for the effect of ratio of initial horizontal stress to vertical stress (Kini). The proposed equations can predict the cross-anisotropic resilient properties for various stress paths corresponding to initial isotropic/anisotropic stress conditions. </p> <p> In order to provide a more comprehensive insight into the complex resilient properties of granular materials along different stress/strain paths for various initial stress states, a micromechanics approach was introduced to back-calculate the degree of fabric anisotropy. The variations of fabric with stress path, initial stress state and final stress state (i.e., state which corresponds to the peak stress during cyclic loading) were investigated. To provide a reliable prediction of initial/inherent fabric anisotropy and fabric evolution in constitutive s with embedded microstructure, an evolution law of fabric anisotropy was developed. </p> / Thesis / Doctor of Philosophy (PhD)

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