Survey of the diagenesis process and effect these process on reservoir quality of the Kangan formation in South Pars Field

Kangan and Upper Dalan formations are forming reservoir sequence of the South Pars field. Litology of the kangan formation is carbonate and (limestone and dolomite with anhydrite intervals), so digenetic processes were very active in this formation and these processes have changeed the reservoir quality. Importances of the digenetic process are including dissolution, calcite cements, dolomitization, anhydritization, physical and chemical compaction and fracturing

Day-ahead Energy Management for Hybrid Electric Vessel with Different PEM Fuel Cell Modular Configurations

The increasing demand for decarbonization of marine transportation motivates the utilization of low-carbon resources. Among different options, fuel cells are drawing attention. The selection of fuel cell (FC) and the design of energy management strategy would have a great impact on the vessel’s operational efficiency, and thereby needs to be considered carefully. The objective of this paper is to develop energy management system (EMS) to reduce the fuel consumption of a hybrid fuel cell/battery ship. To this end, a day-ahead EMS scheme is proposed that takes full use of information including ship cruising routines and the degradation status of the fuel cell modules. The developed EMS is optimization-based and conducted off-line to provide guideline for the next-day power generation plan. In addition, three power allocating strategies across the multiple fuel cell modules are considered and compared (equal, independent, and sequential). A sequential rotation procedure is proposed to reduce the degradation rates of the fuel cell modules. Simulation results show that the proposed EMS can effectively improve the fuel economy of the hybrid ship while enhancing sufficient energy backup throughout the full voyage. In addition, comparisons between different FC configurations implies that the independent distribution has the highest fuel efficiency, and with the proposed rotation procedure, the sequential distribution can effectively improve the fuel efficiency by up to 23.2%

Essays on Capital Structure

Chapter 2 analyses the relationship between capital structure and industry classification of Swedish firms. This study also analyses the determinants of the capital structure at the industry level. Since the assumption required for a parametric analysis of variances are not satisfied, a nonparametric method is applied to test for cross-industry differences in capital structure. The results show that leverage varies significantly across industries. However, the multiple comparison analysis reveals that the significance of the result is mainly due to the construction and real estate industries. Analysis of some determinants of the capital structure at the industry level, with a descriptive method, verifies that the variation of debt ratios has almost the same pattern as the variation of the collateral value of the firms’ assets. Chapter 3 presents an analysis of the relationship between a firm’s characteristics and its choice of capital structure. A large number of hypotheses of different classes of theories are tested. To reduce deficiencies resulting from using a single indicator for attributes which cannot be directly observed, I apply the LISREL method of structural equation modeling. Furthermore, the Extreme Bound Analysis is applied to test for fragility of the estimated coefficients to changes in the number of explanatory variables of the model. The results show that growth, size, collateral value of the assets, and managers’ shareholding positively affect firm leverage, while the effect of profitability on leverage is negative. Chapter 4 studies determinants of the firm leverage during the economic downturn in Sweden 1989-1992. I use a panel data framework to capture both cross-sectional and intertemporal relationships between firm leverage and its determinants. In the first part, I use a descriptive analysis to study variations in mean leverage ratios during the period 1988 to 1992. In the second part, a regression analysis is applied to find variables which explain variations in firm leverage during the recession. The model allows for firm and time effects as well as time varying coefficients. The consistency and efficiency of the estimators regarding problems such as self selection bias and heteroscedasticity are taken into account. Among other things, I find that dividend payments and stock returns affect firms’ leverage negatively. Chapter 5 studies the relationships between firm performance and leverage during the economic recession in Sweden and tests the hypothesis that highly leveraged firms lose market shares to their less leveraged rivals in an industry downturn. I apply both parametric and semiparametric regression methods to analyze the relationships between firm performance and leverage. I find that the highly leveraged firms in distressed industries face relatively lower sales growth and stock returns, while seemingly able to retain a relatively higher growth in profitability. The finding suggests that the decline in sales of the highly leveraged firms might be a result of managers’ preferences to decrease the activity of product lines with low profitability

A Conditional Asset Pricing Model with the Optimal Orthogonal Portfolio

This paper employs a conditional asset-pricing model based on the optimal orthogonal portfolio approach to construct a factor portfolio that embodies all the latent factors important for pricing a given set of test assets. The advantage of this portfolio to the anomaly related mimicking portfolios is its ability to separate out the components of average return that are not related to the return covariation. The performance of this portfolio is evaluated against several conventional factors, using both cross-sectional and time-series regression approaches, as well as the Hansen and Jagannathan (1997) distance measure. Its strong out-of-sample results indicate that our suggested methodology may have important applications in risk management, portfolio selection and performance evaluation