Camino González

Reliability analysis for systems with large hydro resources in a deregulated electric power market

This work describes a procedure that determines the optimal allocation for the yearly energy resulting from random water inflows to the different subperiods of a year so that the expected benefits are maximized. Its main idea is to distribute the energy stored in reservoirs in each period into two parts: one is directly sold in the energy market, while the other is made available to cover any unplanned outages of thermal units. The method proposed fulfills two objectives, to distribute the hydro energy optimally according to economic criteria and to assess the impact of new market rules on the reliability of an electric system. The procedure will be illustrated by an example based on the Spanish generating system.

Bayesian acceptance sampling plans following economic criteria: An application to paper pulp manufacturing

The main purposes of this paper are to derive Bayesian acceptance sampling plans regarding the number of defects per unit of product, and to illustrate how to apply the methodology to the paper pulp industry. The sampling plans are obtained following an economic criterion: minimize the expected total cost of quality. It has been assumed that the number of defects per unit of product follows a Poisson distribution with process average 5 , whose prior information is described either for a gamma or for a non- informative distribution. The expected total cost of quality is composed of three independent components: inspection, acceptance and rejection. Both quadratic and step-loss functions have been used to quantify the cost incurred for the acceptance of a lot containing units with defects. Combining the prior information on 5 with the loss functions, four different sampling plans are obtained. When the quadratic-loss function is used, an analytical relation between the optimum settings of the sample size and the acceptance number is derived. The robustness analysis indicates that the sampling plans obtained are robust with respect to the prior distribution of the process average as well as to the misspecification of its mean and variance.

Long-lived activity of elements: Effect of new activation cross- sections and their uncertainties on the selection of materials for IFE reactors

Activation calculations considering the neutron environment of the first structural wall (FSW) of the inertial fusion energy (IFE) reactor HYLIFE-II are performed for each of the natural elements from H to Bi. Results are used to rank the elements under waste management considerations. The concentration limits (CLs) corresponding to hands-on recycling, remote recycling and shallow land burial (SLB) are computed by using the recently upgraded IAEA activation data library FENDL/A-2.0. Concentration limits are also computed using earlier activation libraries, such as EAF-3.1 and EAF-4.1, to assess the impact of using FENDL on activation studies for fusion. In addition, the accuracy of activation predictions based on FENDL is assessed by computing the uncertainties on the production of the nuclides dominating the long-lived activity of several important elements.

Leveling reliability in systems with large hydro resources

Reliability analysis of a generating system is established in terms of the reliability characteristics of the different units in the system and in terms of the demand of energy to be satisfied. When the analysis is performed for the long-term (one year or more duration periods), the maintenance needs of thermal units as well as the time distribution of resources for units with energy restrictions, must also be taken into account. This paper describes a method for determining the optimal strategy for allocating the yearly energy resulting from random water inflows to the different subperiods of a year so that the reliability for all the subperiods is leveled. A characteristic feature of the method is that the uncertainty inherent in forecasting future available hydroenergy is transferred to the reliability index. The procedure is illustrated by an example prepared using the Spanish generating system.

Student academic performance stochastic simulator based on the Monte Carlo method

Abstract In this paper, a computer-based tool is developed to analyze student performance along a given curriculum. The proposed software makes use of historical data to compute passing/failing probabilities and simulates future student academic performance based on stochastic programming methods (Monte Carlo) according to the specific university regulations. This allows to compute the academic performance rates for the specific subjects of the curriculum for each semester, as well as the overall rates (the set of subjects in the semester), which are the efficiency rate and the success rate. Additionally, we compute the rates for the Bachelors degree, which are the graduation rate measured as the percentage of students who finish as scheduled or taking an extra year and the efficiency rate (measured as the percentage of credits of the curriculum with respect to the credits really taken). In Spain, these metrics have been defined by the National Quality Evaluation and Accreditation Agency (ANECA). Moreover, the sensitivity of the performance metrics to some of the parameters of the simulator is analyzed using statistical tools (Design of Experiments). The simulator has been adapted to the curriculum characteristics of the Bachelor in Engineering Technologies at the Technical University of Madrid (UPM).

Long-term generation scheduling in systems with large hydro resources in a deregulated electric power market

This work describes a procedure that determines the optimal allocation for the yearly energy resulting from random water inflows to the different subperiods of a year so that the expected benefits are maximized. Its main idea is to distribute the energy stored in reservoirs in each period into two parts: one is directly sold in the energy market, while the other is made available to cover any unplanned outages of thermal units. The method proposed fulfills two objectives, to distribute the hydro energy optimally according to economic criteria and at the same time to maximize the reliability of the system. The procedure is illustrated by an example based on the Spanish generating system.

Reliability evaluation for hydrothermal generating systems:: Application to the Spanish case

Abstract Reliability analysis of hydrothermal generating systems usually includes the calculation of annual reliability indicators. This work describes a methodology to evaluate annual reliability taking into account the maintenance program of thermal units and the allocation of hydroenergy to the different subperiods of the year. The procedure takes advantage of the flexibility of hydro units to level the usual reliability indicators along the period of analysis. As an example, the analysis of the Spanish power system is presented.

The kinetics of the reactions of tellurium with stainless steel surfaces and silver aerosols

Abstract Tellurium is a very reactive fission product having great importance because of its own contribution to the health hazard if it is released to the environment and the fact that it is the precursor of decay chains involving iodine. This paper describes a new model to analyze and quantify the chemical behavior of the tellurium fission product in the primary system of pressurized water reactors under severe accident conditions. The great uncertainty on tellurium chemical behavior and the lack of specific experimental evidences suggest the need of a theoretical approach to the problem. The model quantifies the chemical interaction of tellurium vapors with silver aerosols and with the stainless steel of the pipes and structural surfaces. It is also aimed to determine the effect of oxide layers on the reaction rates. All these phenomena alter the transport through the primary system and modify the source term. Hence, the importance of an adequate description of these chemical processes. The model has been incorporated into the RAFT 1.1 transport code and has been verified and validated by using the results and boundary conditions of MARVIKEN Aerosol Transport Test 4. The results show their good agreement with the experimental data.

Obtaining the confounding pattern for 2k-p experiments

We describe a simple method for identifying the confounding pattern for 2k-p experiments when the design matrix is the only available information. This problem arises when one is interested in the study of a published design selected using Taguchis methodology. The proposed method is very simple and, in most practical situations, it can be applied by hand, especially if the design matrix is in standard order. In this sense, it differs from the alias matrix based methods in that it does not require the use of a computer or specialized matrix manipulation software.