This research investigates approaches to improve the performance of multi-agent based simulation (MABS) applications executed in distributed computing environments. MABS is a type of micro-level simulation used to study dynamic systems consisting of interacting entities, and in some cases, the number of the simulated entities can be very large. Most of the existing publicly available MABS tools are single-threaded desktop applications that are not suited for distributed execution. For this reason, general-purpose multi-agent platforms with multi-threading support are sometimes used for deploying MABS on distributed resources. However, these platforms do not scale well for large simulations due to huge communication overheads. In this research, different strategies to deploy large scale MABS in distributed environments are explored, e.g., tuning existing multi-agent platforms, porting single-threaded MABS tools to distributed environment, and implementing a service oriented architecture (SOA) deployment model. Although the factors affecting the performance of distributed applications are well known, the relative significance of the factors is dependent on the architecture of the application and the behaviour of the execution environment. We developed mathematical performance models to understand the influence of these factors and, to analyze the execution characteristics of MABS. These performance models are then used to formulate algorithms for resource management and application tuning decisions. The most important performance improvement solutions achieved in this thesis include: predictive estimation of optimal resource requirements, heuristics for generation of agent reallocation to reduce communication overhead and, an optimistic synchronization algorithm to minimize time management overhead. Additional application tuning techniques such as agent directory caching and message aggregations for fine-grained simulations are also proposed. These solutions were experimentally validated in different types of distributed computing environments. Another contribution of this research is that all improvement measures proposed in this work are implemented on the application level. It is often the case that the improvement measures should not affect the configuration of the computing and communication resources on which the application runs. Such application level optimizations are useful for application developers and users who have limited access to remote resources and lack authorization to carry out resource level optimizations.

8 pp. / The land application (non-hazardous sewage sludge) biosolids has been in practice in Arizona since the 60s.

The crop growth rate (CGR); the relative growth rate (RGR); seed yield; plant uptake of N, P, K, Ca, Mg, Fe, and Na; and the water use efficiency (WUE) were studied in relation to N fertilizer and water application rate interactions in trickle-irrigated cotton. Increasing water application rate significantly increased CGR, but no significant differences were detected among the RGR values at the various water levels. Nitrogen fertilizer additions significantly increased the CGR. Nitrogen and water applications significantly increased seed yield, however, the effect of the interaction between N and water was not significant. Water levels had a positive significant effect on the cotton reproductive growth. Increased N and water significantly increased total N-uptake by cotton plants. Nitrogen additions significantly increased N% of leaves, burrs and seed. However, N% of stem was significantly reduced with high N applications. Total uptake of P, K, Ca, and Mg significantly increased with the increased application of N and water. Addition of 1.2 consumptive use (Cu) irrigation rate significantly increased P% in cotton stems, however, K% in stem was reduced. The irrigation rate of 0.9 CU and 1.2 CU significantly increased Mg% in both leaves and stems. Nitrogen application rates of 224 and 336 kg N/ha significantly decreased Mg% in leaves and stems. Increasing the irrigation rate from 0.9 CU to 1.2(1.3) CU reduced the WUE by cotton plants. However, WUE appeared to increase as N fertilizer increased up to 33 kg N/ha with water level of 0.9 CU.

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Internet-scale dissemination of streaming contents (e.g. live sport games) is most successfully being provided by Multicast Content Delivery Networks (Multicast CDN). Multicast CDN is composed of dedicated servers placed strategically over the Internet, which forward content from origin site to end users. Multicast CDN delivers huge amount of data traffic, and therefore its major operational cost is the ISP cost for network access. Existing Multicast CDNs route user requests to most suitable server based on application performance, such as network delay, server throughput, Internet path congestion etc., without taking into account the potentially high ISP cost it may incur. Multicast CDNs need to control their ISP cost to remain commercially competitive since ISP cost is the most indicative factor affecting the pricing of their services. In this work, we present novel Multicast CDN Request Routing algorithms that minimize ISP cost while still maintaining good network performance for users. Multicast CDN Request Routing algorithms control majority of traffic assigned to servers and therefore directly impacts the ISP cost. ISP cost and user network performances are orthogonal metrics of performance and in order to balance the trade-off between them we introduce overall delay as a constraint to the Multicast CDN Request Routing algorithm. Multicast CDNs are business customers of ISPs and therefore can independently choose to reduce their bills by considering the ways in which ISPs charge. We have designed Request Routing algorithms that exploit the economy of scale in ISP charging function in assigning users to servers. We have developed Request Routing algorithms that exploit the nature of Percentile-based charging used by ISPs to compute the charging volume for traffic generated at server sites. Multicast CDN can cooperate with ISPs to reduce the operational cost of both the parties. Multicast CDN controls how traffic is redirected on the overlay, and that can conflict with how underlying ISPs want the traffic to be forwarded. We have developed Request Routing algorithms that assign users to servers that are available over cheaper IP routes. This reduces the transmission costs for ISPs and these savings can be transferred onto Multicast CDN.

The study is based on the context of project management; the discipline which employs skills and knowledge to achieve project goals through various project activities. The study concentrates on project management applications to deliver low cost houses (LCH) in the Metsimaholo Local Municipality (MLM). The main purpose of project management application is to enable project managers to track the progress of a project that they are working on. Institutions working on a very large project require project management applications to give periodic updates on the progress of the work that is being done on a project. By using a project management application, the process is made somewhat easier, in the sense that a project manager can just refer and check on the progress him/herself. Provision of adequate housing for the homeless and others who are inadequately housed in an attempt to reduce poverty and improve quality of people’s life has been a huge challenge to the South African government, particularly in the MLM over the years. Globally, legislators on the physical infrastructure of Parliament are pushing for the urgent construction of LCH by the government. The abovementioned challenge has resulted in an enormous housing backlog with poverty, unemployment, economic stagnation and negative behaviour. Financial constrains are seen to escalate costs and this makes the task even more enormous. The hypothesis for this study indicated that MLM does not possess sufficient institutional capacity to implement project management for the effective delivery of low cost housing. The hypothesis and research objectives of the study were validated by means of literature review and empirical surveys. Thirty-four (34) semi structured questionnaires were used to interview participants in the provision of LCH in MLM. The study is made up of five chapters. The study specifically focused on the application of project management to deliver LCH in the Metsimaholo Local Municipality (MLM). •This study contends that the application of project management in the public service sector to deliver goods and services has not been scientifically applied in a conscience and systematic manner. •In the MLM the national, provincial and the municipality efforts are challenged to provide houses for the homeless. •The increasing population in the MLM has resulted in an enormous housing backlog with poverty, unemployment, and economic stagnation. •The high demand for housing in the MLM brings about financial constrains and makes the task even more enormous. •It is realised through this study that the application of project management is lacking; whereby important pillars of project based outputs such as time, quality and cost are not necessarily the resultant finished products of the community tend to inherit. It is evident from the above that while the MLM has a mandate to provide service delivery it is limited by protocol to take full responsibility in the provision of low cost houses. The provision of LCH requires strengthened co-operative governance in the Free State Province, since the three spheres have important roles to play. In the face of the huge backlogs in housing and human settlement provision, the country urgently needs to develop the technical knowledge and skills necessary to fast track housing delivery. / M, Development and Management, Public Management and Administration, North-West University, Vaal Triangle Campus, 2012

Web applications have come a long way both in terms of adoption to provide information and services and in terms of the technologies to develop them. With the emergence of richer and more advanced technologies such as Ajax, web applications have become more interactive, responsive and user friendly. These applications, often called Rich Internet Applications (RIAs) changed the traditional web applications in two primary ways: Dynamic manipulation of client side state and Asynchronous communication with the server. At the same time, such techniques also introduce new challenges. Among these challenges, an important one is the difficulty of automatically crawling these new applications. Crawling is not only important for indexing the contents but also critical to web application assessment such as testing for security vulnerabilities or accessibility. Traditional crawlers are no longer sufficient for these newer technologies and crawling in RIAs is either inexistent or far from perfect. There is a need for an efficient crawler for web applications developed using these new technologies. Further, as more and more enterprises use these new technologies to provide their services, the requirement for a better crawler becomes inevitable. This thesis studies the problems associated with crawling RIAs. Crawling RIAs is fundamentally more difficult than crawling traditional multi-page web applications. The thesis also presents an efficient RIA crawling strategy and compares it with existing methods.