The subject of the “The Computer Network Design” thesis is the analysis of the current company status and a detailed analysis of its possible improvement. The present status, company demands and the brief summary of available technologies for proposed solution have been described. The optimal option for the company has been chosen. Current company costs have been analyzed and savings solution for both monthly costs for maintaining the network and purchasing cost for computer technology itself.

The interruption cost for one hour of a petrochemical plant is 33 times higher than that of the average interruption cost for industrial plants across all industries. In addition to the high cost of loss of production, interruptions to the operations of petrochemical and gas-toliquid plants pose safety and environmental hazards. Thus it is necessary to better understand the reliability requirements of petrochemical and gas-to-liquid plants. This study investigated the reliability of electrical distribution networks used in petrochemical and gas-to-liquid plants compared to those used in other industrial plants. A model was developed that can be used to establish the adequacy of the reliability of a distribution network in terms of the components and network topologies used. This model was validated against data that had been collected by the IEEE and applied to an actual petrochemical plant. Over 19 years’ worth of data regarding the trips that have occurred on the distribution network of an existing petrochemical plant was collected and manipulated in order to calculate the reliability indices associated with the equipment used to make up thisRecommended Practice for the Design of Reliable Industrial and Commercial Power Systems. The cost of loss of production and the capital costs associated with increased reliability were calculated for a section of the existing petrochemical plant. The reliability associated with different network topologies that could possibly be used to supply power to this section of the plant were modelled using an appropriate software package. The resulting total cost of ownership over the life of the plant associated with each topology was then calculated in order to establish which network topology is the most appropriate for petrochemical and gas-to-liquid plants. It was concluded the components that affect the reliability of an industrial distribution network are different to those that affect a utility distribution network. These components were listed and compared. It was found that the reliability indices that were calculated for the components that affect the reliability of a petrochemical plant were similar to those provided by the IEEE. 17 out of 20 of the indices that were calculated were within the required factor of deviation. Generally the failure rates of components used in petrochemical plants were very similar to those given in the IEEE Gold Book, while the MTTR’s for the components used in petrochemical plants were found to be slightly better than those given in the IEEE Gold Book. The effect of network topology was found to be significant, with small changes in the topology of a network resulting in large variations in the reliability of the network. It was also found that the most appropriate type of network topology to use in the design of the electrical distribution network of a petrochemical plant is the dual radial network. This is the most conservative of the commonly used network topologies and is the one that is currently used in the existing plant that was studied. Due to the high cost of loss of production in petrochemical plants it was established that any incremental improvement in the reliability of the dual radial network would be beneficial to the total cost of ownership of such a plant. Such incremental improvement of the reliability of the distribution network could be cost effectively achieved by adopting a conservative maintenance strategy and the establishment of a conservative spares inventory. Before this study was undertaken, there was no literature around the reliability of electrical distribution networks that focused specifically on petrochemical and gas-to-liquid plants. This study produced a set of reliability indices and a model that electrical engineers can use in the reliability analysis of petrochemical and gas-to-liquid plants. Furthermore it shows that, because the cost of loss of production in petrochemical plants is so high, the most conservative distribution network design and maintenance philosophies should always be used. distribution network. These reliability indices were compared to those given by the IEEE / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted

Network documentation is often a low-priority task at many companies. Despite this, there are many benefits that should be considered against the fact that it is a comprehensive job. Good network documentation can provide companies the opportunity to reduce dependence on individuals, take proactive decisions and save money. Network documentation mainly consist of physical and/or logical topology descriptions that describes the logical and/or physical layout of the network. These so-called architectural views focus on technology rather than the services and features that the company's network provides. To simplify communication between stakeholders with different areas of knowledge, e.g. between an engineers and corporate management, I propose a model that complement traditional visual description of a network. With the help of viewpoint frameworks such as Kruchten's "4+1" model, I want to visualize relationships between corporate services, business processes, applications and the underlying infrastructure. A qualitative case study at a company with needs of network documentation has resulted in a prototype, a viewpoint framework, based on concepts of enterprise architecture. Analyzing a use case together with the prototype demonstrated that the prototype can visualize relationships between different layers in an organization. The prototype can be used as a starting point or guidance for those who want to document architecture of an enterprise network. The prototype can serve as means of communication in order to justify the investment that in turn ensures a modern energy-efficient operating environment that creates conditions for sustainable information- and communication technology. / Nätverksdokumentation är ofta lågt prioriterat på många företag idag. Men det finns många fördelar som borde vägas mot det faktum att det är ett omfattande jobb. Bra nätverksdokumentation kan ge företag möjligheten att minska personberoende, ta proaktiva beslut och spara pengar. Nätverksdokumentation består huvudsakligen av fysiska och/eller logiska topologidiagram, som beskriver nätverkets utformning. Dessa så kallade vyer fokuserar mer på teknik än de tjänster och funktioner som företagets nätverk tillhandahåller. För att förenkla kommunikation mellan olika intressenter med olika kunskapsbakgrund, t.ex. mellan ingenjörer och ledningen på ett företag, föreslår jag en modell som kompletterar den traditionella visuella beskrivningen av ett nätverk. Med hjälp av ramverk för vyer som t.ex. Kruchtens "4+1" modell, vill jag synliggöra samband mellan företagets tjänster, affärsprocesser, applikationer och den underliggande infrastrukturen. En kvalitativ fallstudie hos ett företag med behov av nätverksdokumentation har resulterat i en prototyp, ett ramverk för vyer, som bygger på koncept inom verksamhetsarkitektur. Analys av ett användarfall med prototypen som underlag demonstrerade att modellen kan synliggöra samband mellan olika skikt i en organisation. Prototypen kan användas som utgångspunkt för den som vill dokumentera arkitekturen hos ett företagsnätverk. Min modell kan fungera som ett kommunikationsmedel för att kunna motivera investeringar i nätverket, som i sin tur säkerställer en modern driftmiljö som skapar förutsättningar för hållbar informations- och kommunikationsteknik.

The world is changing, what has been known to work has been put to the test when both the geopolitical and the environmental climate are changing. War, a pandemic, material shortage, financial difficulties and an overall dis- tressed global transportation sector have shown that the ever-more important topic of resilience is crucial to stay relevant in today’s competitive markets. Companies are therefore switching focus towards ensuring sufficient supply chain resilience capabilities to handle these ever-changing situations on the global market.  In this thesis, we focus on how Volvo SML is working with resilience today, and how graph theory and optimisation can be useful tools when analysing a supply chain’s resilience. We made a qualitative analysis by conducting inter- views with employees and comparing our findings with capabilities related to resilience. In addition, we conducted a quantitative analysis by constructing a simulation of the supply chain, comparing two topology metrics and two op- timisation metrics, to analyse the robustness of the aftermarket supply chain.  We analysed the data and summarised the insights gathered from the inter- views using a resilience capability framework. Volvo SML proved to be agile and reactive when dealing with disruptions but is missing some key capabil- ities during the pre-and post-disruption phases. Some areas of improvement we identified were: robustness, collaboration and redundancy. We proved that the simulation is useful when evaluating the robustness of a supply chain, and we showed that a more flexible way of working would improve the overall robustness of Volvo SML’s aftermarket supply chain.

Phan (2003)等人的研究首先採用網路結構的觀點，來進行在獨占市場下的消費行為分析。本文延伸Phan等人的研究，採用多樣性的不同網路結構，特別是以「無標度網路」(scale-free)作為市場背後的網路結構，藉此來探討網路對於市場需求行為的影響。同時，為了有效地進行量化分析，我們建立了一些數學公式，以便能夠精準地比較不同網路對於需求面的影響程度，其中包含了消費者剩餘、雪崩效果和磁滯效果等。在實驗結果中，我們發現網路結構的確會影響到消費行為的表現，並且當市場規模變大時，仍存在著一些因網路不同而有的差異性。 / The economic implications of network topologies are studied via a monopolist's model of market networks originally proposed by Phan, et al. (2003). By embedding the market into a larger collection of network topologies, in particular, a class of scale-free networks, we extend the early analysis built upon a class of ring networks. To facilitate the study of the impacts of network topologies upon market demand, various measures concerning social welfare (the consumer's surplus), the avalanche effect, and the hysteresis effect, are formally established. Comparisons based on these measures show that network topologies matter, and their implied differences will remain even when the network size becomes large.

Approved for public release, distribution is unlimited / Wireless mesh networking has emerged as the successor of the traditional ad hoc networks. New technological advances, the standardization of protocols and interfaces and the maturity of key components have made it possible for current mesh research groups to set goals that are really close to the world's expectations. The objective of this research is to design and implement a simulation toolkit for wireless mesh clusters that can be used as an additional performance evaluation technique for the Tactical Network Topology program of Naval Postgraduate School. This toolkit is implemented in the OPNET simulation environment and it incorporates various nodes running different ad hoc routing protocols. Furthermore, the investigation of a suitable combination of protocols for the Tactical Network Topology is achieved by creating scenarios and running a number of simulations using the mesh toolkit. / Captain, Hellenic Air Force

Approved for public release, distribution is unlimited / Wireless mesh mobile ad hoc networks (MANETs) provide the military with the opportunity to spread information superiority to the tactical battlespace in support of network-centric warfare (NCW). These mesh networks provide the tactical networking framework for providing improved situational awareness through ubiquitous sharing of information including remote sensor and targeting data. The Naval Postgraduate School's Tactical Network Topology (TNT) project sponsored by US Special Operations Command seeks to adapt commercial off the shelf (COTS) information technology for use in military operational environments. These TNT experiments rely on a variety of airborne nodes including tethered balloon and UAVs such as the Tern to provide reachback from nodes on the ground to the Tactical Operations Center (TOC) as well as to simulate the information and traffic streams expected from UAVs conducting surveillance missions and fixed persistent sensor nodes. Airborne mesh nodes have unique requirements that can be implemented with COTS technology including single board computers and compact flash. / Lieutenant, United States Navy

Approved for public release, distribution is unlimited / The objective of this research is to analyze the network performance and sensor functionality, efficacy and usability of IEEE 802.x wireless MESH networks within a DoD Tactical network environment. Multiple sensor configurations operating with wireless MESH network technologies will be researched and analyzed for performance in expeditionary environment situations. Specifically, this thesis will attempt establish the foundation for the development of wireless MESH "network health" models by examining the performance of sensors operating within a MESH network and define which network performance metrics equate to good quality of service. This research will experiment with different application, sensor, and network configurations of currently available COTS components, such as, voice, video and data hardware. This thesis will lay the groundwork for wireless network MESH predictability, which will enable the optimal use of sensors within a tactical network environment. / Lieutenant Commander, United States Navy

Peer-to-peer networks and mobile ad hoc networks are emerging distributed networks that share several similarities. Fundamental among these similarities is the decentralized role of each participating node to route messages on behalf of other nodes, and thereby, collectively realizing communication between any pair of nodes. Messages are routed on a topology graph that is determined by the peer relationship between nodes. Although routing is fairly straightforward when the topology graph is static, dynamic variations in the peer relationship that often occur in peer-to-peer and mobile ad hoc networks present challenges to routing. In this thesis, we examine the interplay between routing messages and network topology design in two classes of these networks -- unstructured peer-to-peer networks and sparsely-connected mobile ad hoc networks. In unstructured peer-to-peer networks, we add structure to overlay topologies to support file sharing. Specifically, we investigate the advantages of designing overlay topologies with small-world properties to improve (a) search protocol performance and (b) network utilization. We show, using simulation, that "small-world-like" overlay topologies where every node has many close neighbors and few random neighbors exhibit high chances of locating files close to the source of file search query. This improvement in search protocol performance is achieved while decreasing the traffic load on the links in the underlying network. In the context of sparsely-connected mobile ad hoc networks where nodes provide connectivity via mobility, we present a protocol for routing in space and time where the message forwarding decision involves not only where to forward (space), but also when to forward (time). We introduce space-time routing tables and develop methods to compute these routing tables for those instances of ad hoc networks where node mobility is predictable over either a finite horizon or indefinitely due to periodicity in node motion. Furthermore, when the node mobility is unpredictable, we investigate several forwarding heuristics to address the scarcity in transmission opportunities in these sparsely-connected ad hoc networks. In particular, we present the advantages of fragmenting messages and augmenting them with erasure codes to improve the end-to-end message delivery performance.

This dissertation focuses on the material transport system design problem (MTSDP), integrating decisions of technology selection and flow network design. This research is motivated by the design of material transport systems (MTS) in manufacturing plants. The objective is to design a MTS with minimum lifetime costs, subject to service requirements, flow network restrictions, and limited resources. We characterize the MTSDP from the perspectives of task requirements, transport technology, and space utilization. A classification is proposed for transport technologies such that instances in the same class share the same properties, and a decision framework is proposed to emphasize the inter-relationships of three major decisions: task clustering, network connecting, and technology selection. We consider fixed and variable costs, arc capacities, and empty travel in our formulations. We propose two solution approaches for the MTSDP. The first is the compact formulation (CF) approach where the three major decisions are handled by a mixed integer non-linear programming (MINLP) formulation. Relaxation techniques are applied to linearize the model. The solution of the resulting linear formulation (MILP) provides a lower bound to that of MINLP. A tightened formulation reduces the computational time by a factor of 3.85. The experiment also shows that when control system costs are significant, designs with multiple-task clusters are more economical than those restricted to single-task clusters. The other approach is clustering/set partition (CSP), where the three decisions are decomposed and solved sequentially. In an example MTS design problem, three methods are compared: CSP, a GREEDY approach from the literature, and enumeration. CSP finds the optimal solution, while GREEDY results in 31% greater costs. A similar comparison with another example is made for the CF and CSP approaches. We apply the CSP approach in a case problem, using data from an auto parts manufacturer. We include flow path crossing constraints and perform experiments to determine solution quality over a range of small problem sizes. The largest difference from optimality is 3.34%, and the average is 0.98%. More importantly, based on these experiments, it seems there is no evidence that the difference percentage grows with an increase in the number of tasks.