A flexible workforce or a versatile machine is employed to perform various types of operations. Often these resources are associated with setups. Whenever a worker or machine switches from processing one type of operation to another a setup time may be required although several operations of a same type can be processed in succession after a single setup. The presence of setups gives rise to the problem of choosing batch sizes that are neither too large nor too small. In the last one and a half decade, many researchers have addressed the problem of scheduling with batching. A majority of articles assumes that there is only one type of scarce resource, which is typically machine. Often there can be two scarce resources such as a worker and a machine or a machine and a tool. We propose a resource constrained scheduling model with a single operator and two or more machines. Whenever the operator changes machine, a setup time is required that may be sequence dependent or sequence independent. We consider the two cases of an open shop and a flow shop. In the open shop case, the order in which a job visits the machines is unrestricted. In the flow shop case, every job must visit the machines in the same order. We consider various scheduling objectives. For variable number of machines, many cases are intractable. We discuss some dominance properties that narrow down the search for an optimal schedule. We present a dynamic programming approach which solves a large number of cases. The running time of the dynamic program is polynomial for a fixed number of machines. For the case of two machines, we show that the dominance properties have a nice interpretation. We develop some algorithms and justify their use by establishing running times, comparing the running times with those of the existing algorithms, and testing the performance of the algorithms.

As the next evolutionary step in digital communication systems, mobile ad hoc networks (MANETs) and their specialization like wireless sensor networks (WSNs) have been attracting much interest in both research and industry communities. In MANETs, network nodes can come together and form a network without depending on any pre-existing infrastructure and human intervention. Unfortunately, the salient characteristics of MANETs, in particular the absence of infrastructure and the constrained resources of mobile devices, present enormous challenges when designing security mechanisms in this environment. Without necessary measures, wireless communications are easy to be intercepted and activities of users can be easily traced. This thesis presents our solutions for two important aspects of securing MANETs, namely efficient key management protocols and fast implementations of cryptographic primitives on constrained devices. Due to the tight cost and constrained resources of high-volume mobile devices used in MANETs, it is desirable to employ lightweight and specialized cryptographic primitives for many security applications. Motivated by the design of the well-known Enigma machine, we present a novel ultra-lightweight cryptographic algorithm, referred to as Hummingbird, for resource-constrained devices. Hummingbird can provide the designed security with small block size and is resistant to the most common attacks such as linear and differential cryptanalysis. Furthermore, we also present efficient software implementations of Hummingbird on 4-, 8- and 16-bit microcontrollers from Atmel and Texas Instruments as well as efficient hardware implementations on the low-cost field programmable gate arrays (FPGAs) from Xilinx, respectively. Our experimental results show that after a system initialization phase Hummingbird can achieve up to 147 and 4.7 times faster throughput for a size-optimized and a speed-optimized software implementation, respectively, when compared to the state-of-the-art ultra-lightweight block cipher PRESENT on the similar platforms. In addition, the speed optimized Hummingbird encryption core can achieve a throughput of 160.4 Mbps and the area optimized encryption core only occupies 253 slices on a Spartan-3 XC3S200 FPGA device. Bilinear pairings on the Jacobians of (hyper-)elliptic curves have received considerable attention as a building block for constructing cryptographic schemes in MANETs with new and novel properties. Motivated by the work of Scott, we investigate how to use efficiently computable automorphisms to speed up pairing computations on two families of non-supersingular genus 2 hyperelliptic curves over prime fields. Our findings lead to new variants of Miller's algorithm in which the length of the main loop can be up to 4 times shorter than that of the original Miller's algorithm in the best case. We also generalize Chatterjee et al.'s idea of encapsulating the computation of the line function with the group operations to genus 2 hyperelliptic curves, and derive new explicit formulae for the group operations in projective and new coordinates in the context of pairing computations. Efficient software implementation of computing the Tate pairing on both a supersingular and a non-supersingular genus 2 curve with the same embedding degree of k = 4 is investigated. Combining the new algorithm with known optimization techniques, we show that pairing computations on non-supersingular genus 2 curves over prime fields use up to 55.8% fewer field operations and run about 10% faster than supersingular genus 2 curves for the same security level. As an important part of a key management mechanism, efficient key revocation protocol, which revokes the cryptographic keys of malicious nodes and isolates them from the network, is crucial for the security and robustness of MANETs. We propose a novel self-organized key revocation scheme for MANETs based on the Dirichlet multinomial model and identity-based cryptography. Firmly rooted in statistics, our key revocation scheme provides a theoretically sound basis for nodes analyzing and predicting peers' behavior based on their own observations and other nodes' reports. Considering the difference of malicious behaviors, we proposed to classify the nodes' behavior into three categories, namely good behavior, suspicious behavior and malicious behavior. Each node in the network keeps track of three categories of behavior and updates its knowledge about other nodes' behavior with 3-dimension Dirichlet distribution. Based on its own analysis, each node is able to protect itself from malicious attacks by either revoking the keys of the nodes with malicious behavior or ceasing the communication with the nodes showing suspicious behavior for some time. The attack-resistant properties of the resulting scheme against false accusation attacks launched by independent and collusive adversaries are also analyzed through extensive simulations. In WSNs, broadcast authentication is a crucial security mechanism that allows a multitude of legitimate users to join in and disseminate messages into the networks in a dynamic and authenticated way. During the past few years, several public-key based multi-user broadcast authentication schemes have been proposed in the literature to achieve immediate authentication and to address the security vulnerability intrinsic to μTESLA-like schemes. Unfortunately, the relatively slow signature verification in signature-based broadcast authentication has also incurred a series of problems such as high energy consumption and long verification delay. We propose an efficient technique to accelerate the signature verification in WSNs through the cooperation among sensor nodes. By allowing some sensor nodes to release the intermediate computation results to their neighbors during the signature verification, a large number of sensor nodes can accelerate their signature verification process significantly. When applying our faster signature verification technique to the broadcast authentication in a 4×4 grid-based WSN, a quantitative performance analysis shows that our scheme needs 17.7%~34.5% less energy and runs about 50% faster than the traditional signature verification method.

This dissertation examines a profit-maximizing project selection and scheduling problem. Assume that a set of potentially profitable projects are available, yet limited available resources may not allow all of them to be pursued. Profit profiles for projects are assumed to be non-increasing functions of project completion times, i.e. profit returns are sensitive to time-to-market. Decision needs to be made on which sub-set of projects should be chosen and how resources should be allocated to these projects such that the total profit is maximized.Formal mathematical models are formulated for various versions of the problem, including such ones incorporating a third team formation aspect. Structure of the problem is examined and insights are gained regarding prioritization of project, specifically. Although prioritization is sub-optimal in general, heuristic solution methods based on prioritization are pursued, since the scheduling sub-problem itself is NP-hard.A decomposition heuristic framework is first proposed to obtain good solutions using minimum computational time. Sets of test instances are generated using project network data from well-known source in the literature. Computational runs reveal that three priority rules achieve significantly better profits than the benchmarking random priority rule.Improving upon the prioritization based decomposition heuristic, an implicit enumeration is proposed. This algorithm does not examine all priority sequences, yet guarantees an optimal priority sequence when the computation is completed. Several fathoming rules are proposed to cut back computational time effectively. Comparison to the profits achieved by the best priority rule and the benchmarking random priority rule shows a significant improvement on profits, yet at a cost of reasonable added computation time.Future research areas include identifying general conditions under which prioritization of projects would lead us to an optimal solution. Developing better upper bounds for the implicit enumeration scheme is also of interest. The team formation aspect has yet to be treated computationally. It would also be of interest to consider how synergy deviation information may be fed back to the earlier stages of project selection and scheduling decision. Trade-off between profit and team synergy may also be considered in the future.

This paper discusses the use of diagnostics based on machine learning (ML) within a flight test context. The paper begins by discussing some of the problems associated with instrumenting a test aircraft and how they could be ameliorated using ML-based diagnostics. We then describe a number of types of supervised ML algorithms which can be used in this context. In addition, key practical aspects of applying these algorithms, such as feature engineering and parameter selection, are also discussed. The paper then outlines a real-world application developed by Curtiss-Wright, called Machine Learning for Advanced System Diagnostics (MLASD). This description includes key challenges that were encountered during the development process and how suitable input features were identified. Real-world results are also presented. Finally, we suggest some further applications of ML techniques, in addition to describing other areas of development.

The purpose of this study was to investigate parents' perceptions of the food consumption practices and nutrition-related needs in a resource-constrained community, in terms of daily eating patterns, current knowledge and attitudes with regards to food choice, food production and food preparation, as well as community-based nutrition-related needs and information to be included in an intervention aimed at community-wide health and well-being. The study forms part of a broader research project, which aims to facilitate health and well-being in resource-constrained communities, in support of reaching identified Millennium Development Goals (MDGs) and Sustainable Developmental Goals (SDGs). Interpretivism was utilised as meta-theoretical lens and a qualitative research approach was followed. I selected Bronfenbrenner's Ecosystems Theory as guiding framework for the current study. A Participatory Reflection and Action (PRA) research design was utilised to generate data with 22 purposefully selected parents from three primary schools in the Bronkhorstspruit area. Data were generated and documented through PRA-based workshops, observation, visual techniques, field notes and a reflective journal. Following inductive thematic analysis, five themes and related sub-themes emerged. The first theme relates to the daily eating patterns of the community, reflecting food consumed during breakfast, lunch and dinner. Secondly, healthy eating practices were identified as a theme, indicating that community members had a clear understanding of what healthy eating practices entails, available resources to inform healthy eating practices and current informational needs in terms of healthy eating practices. The third theme highlights food preparation practices, where women take responsibility for food preparation by means of a variety of methods. The fourth theme emphasises food purchasing practices, where community members buy from larger chain-stores, local shops and informal traders. Finally, the fifth theme indicates food production practices, where community members prefer to grow their own vegetables. Based on the findings it can be concluded that this community's food consumption patterns are primarily affected by factors in the macrosystem, namely poverty and unemployment. At the macro-level, access to healthy food, cost of healthy food and the influence of the media are aspects influencing the perceptions and decisions of community members such as parents. Changed food consumption practices and nutrition-related needs within the community may, in turn, effect change in the macrosystem by informing related future interventions. / Dissertation (MEd)--University of Pretoria, 2016. / Educational Psychology / MEd / Unrestricted

This study forms part of a broader research project that involves the investigation of the effect of a health promotion intervention (Win-LIFE) on a resource-constrained community's practices, needs and expectations related to food choice, preparation and production. As part of the Win-LIFE intervention, the South African Life Skills school curriculum was enriched, and the current study followed its implementation and focused on the experiences of 31 Grade 5 learners in a school in the Bronkhorstspruit area. For the purpose of this study I followed a qualitative methodological approach, relied on interpretivism as meta-theory and implemented a case study research design, applying Participatory Reflection and Action (PRA) principles. Data were generated by means of PRA-based activities, supported by observations, and documented through field notes, audio-visual techniques and a reflective journal. Thematic inductive analysis was completed following data generation. Four themes with related sub-themes emerged. The first theme relates to the positive experience of experiential learning. The second theme concerns the role of a supportive facilitator. The third theme entails the positive outcomes of the learning process. The last theme relates to the challenges experienced by the learners. The findings of this study indicate a positive general experience of the enriched Life Skills curriculum by the Grade 5 learners, which led to benefits both proximally and distally in the various spheres in which the learners functioned. Learners demonstrated the ability to acquire knowledge and skills in a way they enjoyed, transferred these to their families, and their motivation to learn increased. / Dissertation (MEd)--University of Pretoria, 2016. / Educational Psychology / MEd / Unrestricted

Girl youth, especially those residing in resource-constrained communities such as Diepsloot, constitute a vulnerable population group because of the daily risks they face (Watts & Zimmerman, 2002). Researchers report that chronic exposure to risks can have a negative impact on girl youth’s ability to cope and adjust (Hawke, 2000). However, interventions focused on addressing risk draw on western paradigms of resilience, not accounting for cultural aspects of resilience. Therefore, understanding how girls in Diepsloot conceptualise risk and resilience is an important step in fostering resilience among girl youth. In the present study, I draw on an ecologically-oriented systemic approach to explore how girl youth from Diepsloot make meaning of risk and resilience during an equine assisted intervention called the Growing Great Girls program. Equine assisted interventions, in particular equine assisted interventions that follow an Equine Assisted Growth and Learning Association model approach, has been found beneficial in promoting resilience among youth (Boyce, 2016). In the present study, equine assisted interventions played an important role in the process of gaining an understanding of risk and resilience from the perspectives of girl youth from Diepsloot. Using a qualitative exploratory case study design, I collected data from eight girl youth from Dieplsoot who attended the Growing Great Girls program over a period of eight weeks. From open-ended focus group interviews, photovoice, journal entries and observations as data sources, I used inductive thematic analysis to interrogate how girl youth make meaning of the risks they face to discover the source and nature of their resilience. Three themes emerged as the research results and included theme 1- individual psychosocial characteristics and family climate, theme 2- community related social issues and theme 3- broader societal issues. The findings of the present study contribute towards a broader understanding of risk and resilience that is ecologically relevant to the lives of girl youth from the Diepsloot community. / Dissertation (MEd)--University of Pretoria, 2017. / Educational Psychology / MEd / Unrestricted

The purpose of this study was to explore and describe the experiences of Grade 5 learners after being taught Natural Sciences by means of an enriched curriculum in the Win-LIFE (Wellness in Lifestyle, Intake, Fitness and Environment intervention) project. My focus thus fell on learners’ voices and perceptions, and more specifically with regard to the knowledge and skills that they gained in the Natural Sciences subject, as a result of a health-promotion intervention. For this purpose, I relied on Bronfenbrenner’s Bio-Ecological model (2005) as theoretical framework, and explored the learners’ experiences in a specific sub-system, being the Natural Sciences classroom and curriculum. I furthermore aimed to gain insight into how this can potentially be applied to other systems such as their home environments and personal lives. I used the interpretivist paradigm as meta-theory and followed a qualitative approach. I selected a case study design, applying Participatory Reflection and Action (PRA) principles, thereby aligning my study’s design to the broader research project for data generation and documentation I relied on multiple data generation sources, such as PRA-based workshops/discussions, observation, field notes, visual data documentation techniques and reflective journals to generate and document data. Following inductive thematic analysis three main themes and related subthemes emerged. Firstly, the experiential learning approach that was followed when implementing the intervention had positive outcomes in terms of learners’ attitudes toward learning, their commitment and self-confidence to make contributions in class, and their experiences of the learning process. Secondly, learners gained the necessary knowledge and skills of the Grade 5 Natural Sciences curriculum, and valued the practical experiences they acquired. In addition to their newly gained knowledge and skills being retained after a year, they finally also transferred the content to their parents, caregivers and family members, and reportedly applied what they had learned at home in their personal lives. Based on the findings of the study I can conclude that the learners experienced the enriched Natural Sciences curriculum in a positive manner and that their experiences resulted in positive outcomes and benefits for themselves and also those in their immediate environment. / Dissertation (MEd)--University of Pretoria, 2017. / Educational Psychology / MEd / Unrestricted

Full implementation of special schools converted into special school resource centres in South Africa need to be finalised by 2021, as specified in the Education White Paper 6. The purpose of special school resource centres is firstly to provide necessary resources for the education and training of learners experiencing serious barriers to learning, and secondly to provide, together with the district-based support teams, guidance and support to full-service schools and main stream schools. Despite these expectations and goals, many special schools are not fully strengthened and functional yet. Role-players involved at special school resource centres often feel unequipped to successfully manage their centres in the absence of human resources, knowledge and infrastructure. Against this background, the purpose of this study was to gain an in-depth understanding on how the asset-based approach could be utilised in supporting (or not) the more efficient functioning of a rural resource-constrained special school resource centre in the North West province, South Africa. The asset-based approach and bio-ecological model was used as conceptual framework for the study. Qualitative research was elected as methodological paradigm and an instrumental case study as research design. Interpretivism was selected as meta-theory. One rural resource-constrained special school resource centre was selected through convenience sampling, and eight participants were purposefully selected. Data was collected with individual semi-structured interviews, a focus group discussion, and observation; and documented in audio recorded verbatim transcripts, photographs, field notes and a research journal. Following thematic data analysis, three main themes emerged: identified assets and resources at the resource-constrained special school resource centre (natural assets and resources, human resources, physical resources, and resources for gardening); challenges at the resource-constrained special school resource centre (limited physical space, challenges related to the use of technology, additional responsibilities and related time constraints, and participants? location in relation to the special school resource centre); ways in which mobilised assets and resources supported the functioning of the resource-constrained special school resource centre (financial support for the special school resource centre, supporting the National School Nutrition Programme, strengthening partnerships that could support the functioning of the special school resource centre, skills development as outcome of the two asset-based projects, and intra and interpersonal qualities as a result of implementing the asset-based approach). It was therefore found that the implementation of the asset-based approach is one way to support the functioning of a resource-constrained special school resource centre. / Dissertation (MEd)--University of Pretoria, 2017. / Educational Psychology / MEd / Unrestricted

This thesis considers the case of mobile crime-reporting systems that have emerged as an effective and efficient data collection method in low and middle-income countries. Analyzing the data, can be helpful in addressing crime. Since law enforcement agencies in resource-constrained context typically do not have the expertise to handle these tasks, a cost-effective strategy is to outsource the data analytics tasks to third-party service providers. However, because of the sensitivity of the data, it is expedient to consider the issue of privacy. More specifically, this thesis considers the issue of finding low-intensive computational solutions to protecting the data even from an "honest-but-curious" service provider, while at the same time generating datasets that can be queried efficiently and reliably. This thesis offers a three-pronged solution approach. Firstly, the creation of a mobile application to facilitate crime reporting in a usable, secure and privacy-preserving manner. The second step proposes a streaming data anonymization algorithm, which analyses reported data based on occurrence rate rather than at a preset time on a static repository. Finally, in the third step the concept of using privacy preferences in creating anonymized datasets was considered. By taking into account user preferences the efficiency of the anonymization process is improved upon, which is beneficial in enabling fast data anonymization. Results from the prototype implementation and usability tests indicate that having a usable and covet crime-reporting application encourages users to declare crime occurrences. Anonymizing streaming data contributes to faster crime resolution times, and user privacy preferences are helpful in relaxing privacy constraints, which makes for more usable data from the querying perspective. This research presents considerable evidence that the concept of a three-pronged solution to addressing the issue of anonymity during crime reporting in a resource-constrained environment is promising. This solution can further assist the law enforcement agencies to partner with third party in deriving useful crime pattern knowledge without infringing on users' privacy. In the future, this research can be extended to more than one low-income or middle-income countries.