Browsing by Subject "correlations"
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Item Analysis of coupled body mooring and fender system(Texas A&M University, 2005-11-01) Girija Sasidharan Pillai, HarishThe hydrodynamic excitation and response behavior of multi-body systems with varying degrees of coupling presents many challenges for designers of offshore structures. In this study, attention is focused upon the analysis and interpretation of experimental data obtained for an unmanned deepwater mini-Tension Leg Platform (mini-TLP) coupled to a tender barge. Each body has its own mooring system and the bodies are connected by two breast lines extending from central points on the mini-TLP to central points on the bow and stern of the tender barge. A fender system is located between the two platforms. Thus the two floating bodies are constrained to move together in surge and yaw while they are free to move independently in heave, roll and pitch with some limitations on sway. The data of the individual records are characterized using statistical moments, including skewness and kurtosis, to examine the degree of non-Gaussian behavior. Correlation analysis and cross spectral analysis are used to investigate the relationships between selected measurements such as the motion of each vessel, tensions in the mooring lines and tendons and the forces on the fenders. The analysis shows that the coupling effects reduce the mooring line and tendon tensions significantly and that the motions of the two vessels influence the line tensions and fender forces. The data distribution patterns followed by the parameters and the corresponding extreme values are also investigated.Item Optimization of a petroleum producing assets portfolio: development of an advanced computer model(2009-05-15) Aibassov, GizatullaPortfolios of contemporary integrated petroleum companies consist of a few dozen Exploration and Production (E&P) projects that are usually spread all over the world. Therefore, it is important not only to manage individual projects by themselves, but to also take into account different interactions between projects in order to manage whole portfolios. This study is the step-by-step representation of the method of optimizing portfolios of risky petroleum E&P projects, an illustrated method based on Markowitz?s Portfolio Theory. This method uses the covariance matrix between projects? expected return in order to optimize their portfolio. The developed computer model consists of four major modules. The first module generates petroleum price forecasts. In our implementation we used the price forecasting method based on Sequential Gaussian Simulation. The second module, Monte Carlo, simulates distribution of reserves and a set of expected production profiles. The third module calculates expected after tax net cash flows and estimates performance indicators for each realization, thus yielding distribution of return for each project. The fourth module estimates covariance between return distributions of individual projects and compiles them into portfolios. Using results of the fourth module, analysts can make their portfolio selection decisions. Thus, an advanced computer model for optimization of the portfolio of petroleum assets has been developed. The model is implemented in a MATLAB? computational environment and allows optimization of the portfolio using three different return measures (NPV, GRR, PI). The model has been successfully applied to the set of synthesized projects yielding reasonable solutions in all three return planes. Analysis of obtained solutions has shown that the given computer model is robust and flexible in terms of input data and output results. Its modular architecture allows further inclusion of complementary ?blocks? that may solve optimization problems utilizing different measures (than considered) of risk and return as well as different input data formats.