Robust decisions in power system investments
The Turkish electrical system has been studied, particularly for the near term investment programme. The objective of the study was to determine the most likely investment alternatives for the next ten-year period, from a cost effectiveness point of view. A dynamic linear programming model was used in representing the national energy system, with special emphasis on the electricity sector. Hydro, coal, nuclear and oil-fired power plants as well as their interconnection investments were modelled. A 27-year planning horizon was defined. The scenario approach was utilized in establishing the effects of different factors, such as foreign currency requirements of projects, nuclear plant costs and nuclear fuel costs, demand growth rates for electricity as well as other fuels, availability of foreign currency and skilled manpower, and the development rates of coal mines, coal power plants and nuclear power plants. After analyzing the results of 24 different scenarios, robust plans for developing the power system are suggested. Other investments that are subject to the realization of certain conditions are also indicated.
Decision analysis in the energy sector
Abstract An optimization model has been developed primarily for the planning of the national energy system. It is also shown, however, that the model can be used as a tool for decision analysis. The dynamic linear programming mini-model includes four primary energy sources and three forms of secondary energy. Decision variables include investment as well as production activities in the refining, conversion, and transmission of energy. The model contains 186 columns and 226 rows. The objective function is the discounted sum of costs of fuels, investments, operating costs, and under-utilized capacity. The model has been used to analyse decisions in the Turkish energy sector for the years 1960-1975, and possible developments for the period 1980-1995. Through the use of this model, the underlying assumptions concerning the import prices of petroleum have been analysed, as well as the impact of a delay in the construction of a large hydro project. Furthermore, the effect of the shadow costs of foreign currency, the consequences of rapid industrialization, rapid economic growth, and substitution among fuels have been investigated. The model is currently being used for the analysis of possible nuclear strategies for Turkey.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.