Using network architecture to describe a biological system is an effective organizational method. The utility of this approach, which generally applies to qualitative models, is enhanced by the addition of quantitative models characterizing the interactions between network nodes. A chromatophore-based signal transduction network is developed, and the highly interconnected major nodes of the network, guanine trisphosphate, adenylate cyclase, and protein kinase A, are identified. These reference nodes serve to partition the network into functional modules, and mechanistic models describing these modules are derived. Three elicitor compounds, forskolin, melanocyte stimulating hormone (MSH), and clonidine, were selected due to their ability to access the signal transduction network at specific reference nodes, and the module configurations corresponding to their mechanisms of action are presented. The chromatophore responses to the three elicitors and to a negative control, L-15 cell medium, were recorded for two experimental blocks consisting of genetically different fish cells. Significant differences in cell responsiveness were evident between the two blocks, but this variability was controlled by the transformation and normalization of the data. The model parameters for each agent were estimated, and the resulting response curves were highly accurate predictors of the changes in apparent cell area, with R-squared values in the 0.88 to 0.96 range. Two examples were presented for the application of a model discovery algorithm, which selects modules from an existing library, generates model output for all valid module configurations, and selects the configurations which best satisfy a fitness function for a given set of target data. The algorithm proved robust to the introduction of different levels of random error in the simulated data sets when applied to a model of the desensitization of a cell membrane receptor, and continued to classify the stochastic data sets correctly even when the underlying rate constants differed significantly from those embedded in the modules. When challenged with the chromatophore data, the model discovery algorithm successfully matched the forskolin and MSH module configurations to the data within the top three models proposed, with less precise classification for the clonidine model. / Graduation date: 2005

An architectural framework is proposed to secure the data link layer (Layer 2) in Internet protocol (IP) over Ethernet networks. In this architecture, a new security inter-layering concept, incorporating cryptographic Layer 2 identities, is introduced. Instead of traditional media access control (MAC) addresses, secure and flexible data link layer identifiers are utilized to securely bind Layer 2 and upper layers. In addition, to create security parameters and negotiate identifiers at the data link layer, a key establishment protocol is presented. Moreover, this architecture incorporates the IEEE 802.1AE standard (MACsec) and uses a key hierarchy similar to the IEEE 802.11i standard for future compatibility of wired and wireless networks. Finally, we provide a security analysis of the new data link layer security architecture.

This thesis, presents a multiprocessor topology, the hierarchical network of hyper-cubes, which has a low diameter, low degree of connectivity and yet exhibits hypercube like versatile characteristics. The hierarchical network of hyper-cubes consists of k-cubes interconnected in two or more hierarchical levels. The network has a hierarchical, expansive, recursive structure with a constant pre-defined building block. The basic building block of the hierarchical network of hyper-cubes comprises of a k-cube of processor elements and a network controller. The hierarchical network of hyper-cubes retains the positive features of the k-cube at different levels of hierarchy and has been found to perform better than the binary hypercube in executing a variety of application problems. The ASCEND/DESCEND class of algorithms can be executed in O(log2 N) parallel steps (N is the number of data elements) on a hierarchical network of hypercubes with N processor elements. A description of the topology of the hierarchical network of hypercubes is presented and its architectural potential in terms of fault-tolerant message routing, executing a class of highly parallel algorithms, and in simulating artificial neural networks is analyzed. Further, the proposed topology is found to be very efficient in executing multinode broadcast and total exchange algorithms. We subsequently, propose an improvisation of the network to counter faults, and explore implementation of artificial neural networks to demonstrate efficient implementation of application problems on the network. The fault-tolerant capabilities of the hierarchical network of hypercubes with two network controllers per k-cube of processor elements are comparable to those of the hypercube and the folded hypercube. We also discuss various issues related to the suitability of multiprocessor architectures for simulating neural networks. Performance analysis of ring, hypercube, mesh and hierarchical network of hypercubes for simulating artificial neural networks is presented. Our studies reveal that the performance of the hierarchical network of hypercubes is better than those of ring, mesh, hypernet and hypercube topologies in implementing artificial neural networks. Design and implementation aspects of hierarchical network of hypercubes based on two schemes, viz., dual-ported RAM communication, and transputers are also presented. Results of simulation studies for robotic applications using neural network paradigms on the transputer-based hierarchical network of hypercubes reveal that the proposed network can produce fast response times of the order of hundred microseconds.

Thesis (Ph.D. (Computer Science)) - Rhodes University, 2008.

Thesis (Ph. D.)--University of California, Riverside, 2008. / Includes abstract. Title from first page of PDF file (viewed February 3, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references. Also issued in print.

M. Tech. Professional Practice in Information Technology. Tshwane University of Technology, 2008. / The application of Information and Communication Technology (ICT) in business environment (profit-making and non-profit-making organisations, and public administration) has given business the power to provide its services faster, smoother, and at extended time than ordinary day working hours especially in the banking industry where the service delivery is expected to be 24 hours a day for seven days a week. Many organisations in today’s’ networked economy, mostly banking organisations, rely on ICT infrastructure to operate. The key to success with technology is not the technology per se, but the ability to manage it well. In sustaining business operations, ICT infrastructure needs to be effectively managed, with the application of tested and proven best practices such as ICT management frameworks for the organisation to benefit from it. This research explores the usage of ICT management frameworks in managing ICT infrastructure in the South African banking industry, where there is a complexity of systems because of combination of different components, some built in-house, and others procured from third-party suppliers. This research study is exploratory, applying the qualitative research approach as research strategy. It applies structured interviews as a tool for collection of primary data from participants, and uses reviews of previous publications on ICT management frameworks for secondary data collection. After a review of collected data, it has been found that: - It is important to ensure effective management of ICT infrastructure by applying best-practices as it is needed in supporting the organisation to achieve its objectives; - Though the use of ICT management frameworks is different from one bank to another, all banking organisations refer to the practices of ICT frameworks to manage their infrastructures and related processes; - Though there is not much difference in the management of ICT infrastructure in banking industry and others industries that rely on ICT for management and service delivery, banking organisations pay more attention to security, continual service delivery, and fast service delivery. Looking at the complexity of ICT infrastructures in major commercial banks investigated, it has been recommended that banks should not only concentrate on the collection of best practices in different frameworks, but also direct their efforts in creating one single framework that addresses business vision, strategies and the managerial system with more concentration on ICT infrastructure for the support of its operations, information management and sharing.

Network virtualization and overlay networks have emerged as powerful tools for improving the flexibility of the Internet. Overlays are used to provide a wide range of useful services in today's networking environment, and they are also viewed as important building blocks for an agile and evolvable future Internet. Regardless of the specific service it provides, an overlay needs assistance in several areas in order to perform properly throughout its existence. This dissertation focuses on the mechanisms underlying the provision of auxiliary support services that perform control and management functions for overlays, such as overlay assignment, resource allocation, overlay monitoring and diagnosis. The priorities and objectives in the design of such mechanisms depend on network conditions and the virtualization environment. We identify opportunities for improvements that can help provide auxiliary services more effectively at different overlay life stages and under varying assumptions. The contributions of this dissertation are the following: 1. An overlay assignment algorithm designed to improve an overlay's diagnosability, which is defined as its property to allow accurate and low-cost fault diagnosis. The main idea is to increase meaningful sharing between overlay links in a controlled manner in order to help localize faults correctly with less effort. 2. A novel definition of bandwidth allocation fairness in the presence of multiple resource sharing overlays, and a routing optimization technique to improve fairness and the satisfaction of overlays. Evaluation analyzes the characteristics of different fair allocation algorithms, and suggests that eliminating bottlenecks via custom routing can be an effective way to improve fairness. 3. An optimization solution to minimize the total cost of monitoring an overlay by determining the optimal mix of overlay and native links to monitor, and an analysis of the effect of topological properties on monitoring cost and the composition of the optimal mix of monitored links. We call our approach multi-layer monitoring and show that it is a flexible approach producing minimal-cost solutions with low errors. 4. A study of virtual network embedding in software defined networks (SDNs), identifying the challenges and opportunities for embedding in the SDN environment, and presenting two VN embedding techniques and their evaluation. One objective is to balance the stress on substrate components, and the other is to minimize the delays between VN controllers and switches. Each technique optimizes embedding for one objective while keeping the other within bounds.

Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2007. / "A dissertation in computer networking and telecommunication networking." Advisor: Deep Medhi. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 24, 2008. Includes bibliographical references (leaves 130-138). Online version of the print edition.

Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Additional advisors: David G. Green, Gary J. Grimes, John L. Hartman IV. Description based on contents viewed Feb. 5, 2008; title from title screen. Includes bibliographical references (p. 110-120).

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Spine title: Authentication models. Bibliography. p. [167-175].