Pedro L. Iglesias

Pipeline start-up with entrapped air

A mathematical model for the assessment of the pressure head maxima that air pockets within a pipeline can originate on start-up is presented. This model is based on a general model addressing the ...

A diversity-enriched variant of discrete PSO applied to the design of water distribution networks

The design of water distribution networks (WDNs) is addressed by using a variant of the particle swarm optimization (PSO) algorithm. This variant, which makes use of a discrete version of PSO already considered by the authors, overcomes one of the PSOs main drawbacks, namely its difficulty in maintaining acceptable levels of population diversity and in balancing local and global searches. The performance of the variant proposed here is investigated by applying the model to solve two standard benchmark problems: the Hanoi new water distribution network and the New York Tunnel water supply system. The results obtained show considerable improvements in both convergence characteristics and the quality of the final solutions, and near-optimal results are consistently achieved at reduced computational cost.

Modelling Water Distribution Networks: From Steady Flow to Water Hammer

Water supply systems modelling constitutes a basic tool for an adequate technical management of those systems. In practical applications, it is frequent to use different models depending on the problem to be analyzed: from the simplest one, the static model, to the most complex one, the elastic inertial model, better known as water hammer.

Computational models calibration: Experiences in environmental engineering studies

Mathematical models are a fundamental tool in the learning process of environmental engineering. These models need to be calibrated in order to be used by future engineers as a simulation tool for the represented problems. This paper deals with the concept of computational models calibration applied to higher environmental engineering studies. In this paper, we depict a methodology to calibrate water quality models, as an educational example that represents the environmental problem of dissolved oxygen in a stream. This methodology is based on defining two types of parameters involved in calibration. First, internal parameters appear in the equations from semi‐empirical estimations and can be found within some intervals. Genetic algorithms are proposed to estimate them. Second, experimental measurements enter into equations as external parameters. They affect the accuracy of the final solutions. Therefore, an uncertainty analysis has to be performed. Finally, a termination criterion for calibration has been proposed, based on the overlap between the confidence intervals of predicted and measured values. By developing this methodology, we provide awareness to our students of the importance of calibration of mathematical models so that they can apply them in their future simulation of environmental problems. Students identify the possible sources of uncertainty at each stage of the environmental model performance and apply them in this particular problem, Genetic Algorithm Techniques, as a computational tool to improve the accuracy of their model predictions.

Generalization of Pump Station Boundary Condition in Hydraulic Transient Simulation

In this paper, a generalized treatment of the equations describing the behavior of a pumping stat ion is presented. It enables the simulation of many reasonable combinations of elements within a pumping station, by using a single routine and one set of state data suitably maintained. Thus, it represents a unified algorithm massively solved that easily accommodates to virtually every condition in a pumping station. Besides, the interpolating method it uses allows to incorporate manufacturers information into dimensionless curves helping plausibly to produce more real results. The interest of the paper is mainly computational. Nevertheless, the scheme we propose enables the joint consideration of a wide range of elements in a pumping station without the need of including short reaches between them. In this way, it is claimed to represent a good improvement for existing packages to model transient analysis in networks.

The Use Of An Interpolation Numerical Wind Model For Regional Air Pollution Dispersion Studies. A Case Of Study

We have elaborated an interpolation numerical wind model to be used as input data in regional air pollution dispersion studies. This model evaluates the principal components for the wind observations and the wind patterns for the grid nodes in a complex terrain by solving a partial differencial equation applying the Finite Element Method. The wind field for every measurement time is obtained as a linear combination of the wind patterns, with coefficients evaluated by means of the simultaneous observations and the principal components. This is part of a study to evaluate the dispersion capacity of air pollution in the Comunidad Valenciana (Spain) related with land use plans.