<p> Nitrogen-based fertilizer industry in United States is undergoing major changes the demand for which is primarily driven by agriculture. Traditionally, this industry sources anhydrous ammonia through imports from Canada and U.S.-Gulf, the latter comprises bulk of imports, or produces domestically to be supplied as is or converted into urea or UAN variations of nitrogen-based fertilizer with various combinations with other minerals. </p><p> With change in composition of crops and increasing acreage of crops that are fertilizer intensive, there is an increased demand for nitrogen-based fertilizer in order to promote foliar growth as a standalone form, for example Urea, or in combination, for example Di-ammonium phosphate (DAP). Second compelling reason for change in industry is reduction in prices of natural-gas, in part due to oil exploration, that makes it cheaper to produce anhydrous ammonia domestically. Anhydrous ammonia is perquisite for making other types of nitrogen-based fertilizer and highly energy intensive. Thus, lower natural-gas prices provide incentive for domestic firms to either expand existing fertilizer plants or opens up the possibility of new entrants. Many companies/firms have recently announced their plans to expand existing plants or open new units, exerting competitive pressure on an industry that already has lot of surplus capacity but highly competitive in terms of production costs and technology used. It is to be noted that natural-gas prices are volatile; therefore, any commitment to expand or open new plant is subject to volatility in demand, natural-gas prices, and import price of fertilizers. </p><p> The purpose of this dissertation is to analyze spatial competition among U.S. nitrogen-based fertilizer plants and their respective market boundaries. This dissertation also derives the structure of the supply chain for nitrogen-based fertilizer in the United States (at macro level); and the stochastic spatial-optimization model to account for risk in random variables. Locational information is used to account for spatial nature of problem, and linear and mixed-integer based optimization techniques are applied to arrive at current and most likely future cases. </p><p> Combination of linear optimization, and mixed-integer, and geographical information systems helps in determining regional areas where competition is expected to be ruinous and most intense; and provide insights on viability of newly announced fertilizer plants that are most likely to be successful and significantly impact the structure of overall supply chain. </p>

This thesis focuses on the new product development (NPD) process and the organizational structure which supports the process. The expected payoff method is borrowed from economic theory and is modified to be able to quantitatively evaluate processes. The method is used to evaluate and compare sequential and concurrent engineering processes. The method is also used to evaluate different organizational structures that support NPD processes. Thus, the relationship between process effectiveness and organizational structure is investigated. Study results are compared with observations of actual NPD processes and organizational structures. A third part of this thesis develops an analysis technique for the study of the dynamic task coupling which takes place in concurrent engineering. The ability to determine a dynamic ordering of tasks is compared to the static ordering given by the Design Structure Matrix method.

This thesis compares the numerical performance of digital control laws implemented in the Z operator, z, and the Euler operator, $ epsilon$ = ${z-1 over T}$ where T is the sampling period, and provides some useful guidelines for estimating the conservative wordlength for relatively low order controllers which are implemented using floating point arithmetic. The relative merits of these two discrete-time operators are studied analytically with regard to coefficient representation and roundoff errors, which are two major sources of numerical error. It is shown in this thesis that the $ epsilon$ operator form has superior performance in the coefficient representation to the z operator form for the sampling rates often used in practice. It is also shown that control laws implemented in the $ epsilon$ operator provide superior performance in the introduction of roundoff errors and in the propagation of these errors through subsequent sampling instants than the z operator, at least for high sampling rates. Extensive numerical simulations are also performed to compare the $ epsilon$ and z forms to obtain useful rules of thumb for estimating the wordlength required by a controller based on the sampling rate and the dynamic characteristics of the controller.

The over, or under-commitment of forces in a combat environment can result in the unnecessary loss of life, and compromise the ability of committed forces to prevail in their missions. Appropriate commitment requires a clear understanding of the capability of available forces, and a key tool in this determination is operational test and evaluation (OT&E). The role of OT&E in the Australian Defence Organisation (ADO), with emphasis on the Royal Australian Air Force (RAAF) is the subject of investigation in this research. / The ADO recognises the need for OT&E throughout the entire life of capability systems, and policy mandating its conduct has been in effect for over a decade. Despite this, Defence and in particular the RAAF, lacks a suitable infrastructure to support the development, and maintenance of high quality OT&E practices. / In trying to implement the Defence directive to 'get on with it', without a definition of what 'it' is, RAAF elements have developed a number of disparate approaches to OT&E. these attempts have largely failed to uphold the principles of OT&E in evaluating capability, and have potentially put lives at stake. Furthermore, the dearth of coordinated practical guidance on the conduct of OT&E has resulted in the continued inability of the RAAF to realise the many potential benefits that a coordinated approach to OT&E has to offer. / This research was thus undertaken to define a framework, supporting integration with capability management processes, which would facilitate the standardised development and maintenance of OT&E through the RAAF. The objectives of the research were achieved, through the definition of a simple, flexible and effective model that could be adapted for ADF-wide implementation. A strategy for implementing the model was also developed, based on the principles of project and change management. In combination, these proposals have provided a sound basis for the RAAF to develop an enduring OT&E capability, and start realising the benefits of high-quality OT&E that is integrated with capability management processes. / Thesis (MEducationbyResearch)--University of South Australia, 2005.

Computing the reliability of a network is a #P-complete problem, therefore estimation by means of simulation often becomes a favourable choice. In modern communication networks, link failure probabilities are usually small and hence network failures become rare events. This poses a challenge to estimate the network reliability. In this thesis we present different techniques for network reliability estimation. There are two main sampling techniques in reliability estimation: combinatorial and permutational sampling. Combinatorial sampling has the advantage of speed but has poor performance in rare event simulations. Permutational sampling gives good simulation performance but at a higher computational cost. We combine the two techniques and propose a hybrid sampling scheme called Tree Cut and Merge. By employing simple bounding together with clever conditional sampling, the TCM scheme achieves over 10(superscript 7) times speed up in certain classes of heterogeneous networks. The Crude Monte Carlo (combinatorial) component in the Tree Cut and Merge scheme may cause problems in some situations. In bad cases, the slow convergence problem re-appears. To address the problem, we modifed the scheme by introducing the Importance Sampling technique. The new Tree Cut and Merge with Importance Sampling scheme maintained the speed advantage of the Tree Cut and Merge and minimizes, at the same time, the potential problems caused by the Crude Monte Carlo component. Associated with the Importance Sampling technique, a new technique called the Cross-Entropy method has been developed in the late 90's to find the optimal Importance Sampling parameters. By employing the Cross-Entropy technique, we propose a new scheme called the Merge Process with Cross-Entropy. The new scheme improves the Merge Process in nearly all classes of network; in contrast, Tree Cut and Merge with Importance Sampling scheme sees the greatest improvement in heterogeneous networks. Besides estimating the reliability of a single network, this thesis also investigates a closely related problem: estimating the difference in reliability of two very similar networks. The problem is closely linked to the applications in the areas of network optimization, network evolution, reconfiguration and recovery, for example. The fact that the probabilities of rare events are hard to estimate makes estimating their difference even more difficult. Coupled and differential sampling techniques are proposed and applied to various schemes in this thesis. They prove to be superior to the conventional independent "estimate and subtract" method. Interestingly, these concepts also lead to new ideas regarding the estimation of the reliability of networks that are similar to networks with polynomially computable reliability. / Thesis (Ph.D.)--School of Mathematical Sciences, 2005.

Thesis (Ph.D.)--University of Pennsylvania, 2007. / Includes bibliographical references.

Thesis (M.S. in Management)--Naval Postgraduate School, March 2009. / Thesis Advisor(s): Hatch, Willam D. ; Enns, John. "March 2009." Description based on title screen as viewed on April 23, 2009. Author(s) subject terms: Civilianization, Cost Analysis, Ministry of National Defense, Department of Defense, Defense Reform, Civilian Personnel, Pay and Compensation Includes bibliographical references (p. 61-63). Also available in print.

Thesis (M.S. in Operations Research)--Naval Postgraduate School, March 2009. / Thesis Advisor(s): McCauley, Michael E. "March 2009." Description based on title screen as viewed on April 23, 2009. Author(s) subject terms: Sopite syndrome, motion sickness, wrist actigraphy Includes bibliographical references (p. 77-82). Also available in print.

Thesis (Master of Computer Science)--Naval Postgraduate School, March 1992. / Thesis Advisor: Kanayama, Yutaka. "March 1992." Includes bibliographical references (p. 94-95). Also available in print.

Thesis (Ph.D.)--Lehigh University, 2008. / Adviser: Lawrence V. Snyder.