The objective of this work is to integrate manufacturing considerations of arc welding processes in the early stages of welded structures design. This is accomplished through the development of a framework that allows design engineers to investigate the appropriate trade-offs between deposition rates, operator factors, deposition efficiency, welding position, accessibility, weldability, and joint design at an early stage in the design. The impact of different decision making alternatives made early in the product life cycle are supported by expected costs. The system details are demonstrated with the major welding processes and hull non-nuclear steels used in construction of surface combatant ships in the United States Navy. / Master of Science

Master of Engineering

Master of Science

A finite element modeling and geometrically nonlinear static analysis of the top portion of a glued-laminated timber dome is presented. The modeling assumptions and analysis procedures are applied to a dome model whose geometry is based on an existing glulam timber dome of 133 ft. span and 18 ft. rise above the tension ring. This dome consists of triangulated network of curved southern pine glulam members connected by steel hubs. The dome is covered with a tongue-and· groove wood decking. The role of decking towards the stability of the overall structure is studied. The lateral resistance of the nail fasteners connecting the beams and the purlins to the decking is considered . The stabilizing effect of the decking is shown to be mathematically analogous to that acting on the beams along the line of the deck attachment. The axial pull, in this study is modeled by truss members. Three distinct analyses are performed for rigid and flexible joints: a linear analysis to check design adequacy of the members, a linearized eigenvalue buckling prediction analysis to estimate the buckling load, and finally an incremental, iterative, geometrically nonlinear analysis to trace the complete response of the structure up to failure. Analyses are done for the structure with and without the decking on top of the beams and purlins to assess the role of decking on the overall stability of the structure. It is shown that decking plays a considerable role in the load-carrying behavior of the whole structure. A discussion of the results is presented and recommendations for future extensions are included. / Master of Engineering

Master of Science

Clearly, nitrocellulose characterization is a difficult task. However, previous investigators have developed the required methodology for application to new studies. Solution properties of nitrocellulose are especially complex, depending on solvent properties, temperature, nitrocellulose molecular weight characteristics and nitrocellulose DOS homogeneity. The realization of the time dependance of these properties has added to the complexity. Mechanical characterization of nitrocellulose propellants appears to be an emerging technology. The morphological intricacy of nitrocellulose propellants in addition to the chemical complexity of nitrocellulose has hampered direct correlation of the polymeric properties of nitrocellulose wi th propellant mechanical behavior and subsequently ballistic performance. / Master of Science

No description available.

This research addresses two important issues facing transportation economists and planners: the relationship between transportation investment and economic development and the methodology for evaluating transportation projects and programs. Transportation is viewed as an important factor which enters the production functions of firms and the consumption functions of individuals. The demand for and the supply of transportation cannot be determined within the transportation system. Changes in the transportation system may have far-reaching and, most importantly, feedback effects that not only generate secondary impacts, tertiary impacts, and so on; but also influence further decisions and, therefore, generate more changes further along in the system. The systems approach is crucial to the identification and quantification of impacts of transportation improvements and to the better understanding of transportation/economic development relationships. System dynamics is used in this research as a tool for modeling and simulating transportation/economic interactions. This research conceptualizes the role of transportation in a broad socioeconomic context and develops a framework for applying the systems approach to the evaluation of transportation investments. Five scenarios examined with the methodology are: highway improvement, corridor development, HOV lane provision, impacts of transportation in a closed economy, and regional impacts of transportation. Conclusions are drawn which signify general policy implications. / Ph. D.

Molecular Orbital calculations on 31 H3:e_mxm+N:e hydronitride molecules containing 3-, 4-, and 6-coordinate X-cations from rows 1-4 of the periodic table yield minimum energy bond lengths, Rt(XN), which reproduce observed bond lengths, Ro(XN), in crystalline nitrides to within o.O₃A, on average. A linear regression analysis of In[Rt(XN)] vs. In(p) with p = air, where a is the Pauling bond strength and r is the row number of the X -cation in the periodic table, gives the equation R(XN) = 1.47p-O.2\ which is shown to reproduce the observed XN bond lengths of Baur (1987) to within o.o9A, on average. This equation is statistically identical to the equation R( XN) 1.49p-O.22, derived from a linear regression analysis ofln[Ro{XN)] vs. In(p), and is similar in form to those obtained for the oxides (R(XO) = 1.39p-O.22) and the sulfides (R(XS) = 1.83p-O.21). / Master of Science

The determinants of the success and failure of futures contracts were investigated. The existing literature on the subject was examined yielding two predominant veins of thought; those attributing the determinants of success to the characteristics of the underlying commodity and those favoring the contractual provisions. The two views were compared and contrasted based upon their respective explanatory merits. Both were found to contain explanatory value but failed to offer an all encompassing theoretic approach. Fifty innovative contracts were examined to categorize the inception behavior of new contracts. The contracts were found to be either very successful, fail miserably, or experience a period of initial success before abrupt cessation of trading. The reasons for each respective category of behavior were examined and highlighted with case studies. Those directly tailorable factors contributing to the potential success of a contract were examined in the context of an exchanges' strategy for innovation. The difficulties of using duplicative contracts to capture interest from existing liquid instruments is highlighted. After developing this solid understanding of contract innovation the existing application of the insurance hypothesis is refuted and an alternate expected money value approach stated. The advantages of this approach and the increased explanatory power are espoused. / Master of Arts