Papers by Richard Peralta
Advances in Water Resources, 1998
A modeling approach is presented that optimizes separate phase recovery of light non-aqueous phas... more A modeling approach is presented that optimizes separate phase recovery of light non-aqueous phase liquids (LNAPL) for a single dual-extraction well in a homogeneous, isotropic unconfined aquifer. A simulation/regression/optimization (S/R/ 0) model is developed to predict, analyze, and optimize the oil recovery process. The approach combines detailed simulation, nonlinear regression, and optimization. The S/ R/O model utilizes nonlinear regression equations describing system response to timevarying water pumping and oil skimming. Regression equations are developed for resjtdual oil volume and free oil volume. The S/R/O model determines optimized timevarying (stepwise) pumping rates which minimize residual oil volume and maximize free oil recovery while causing free oil volume to decrease a specified amount. This S/R/ 0 modeling approach implicitly immobilizes the free product plume by reversing the wa(:er table gradient while achieving containment. Application to a simple representative problem illustrates the S/R/O model utility for problem analysis and remediation design. When compared with the best steady pumping strategies, the optimal stepwise pumping strategy improves free oil recovery by 11.5% and reduces the amount of residual oil left in l.he system due to pumping by 15%. The S/R/O model approach offers promise for enhancing the design of free phase LNAPL recovery systems and to help in making cost-effective operation and management decisions for hydrogeologists, engineers, and regulators. 0 1998 Elsevier Science Limited. All rights reserved.
Ground Water, 1991
A methodology has been developed for identifying hazardous pesticides/site combinations threateni... more A methodology has been developed for identifying hazardous pesticides/site combinations threatening ground-water contamination. Screening methodologies are required to determine which locations and pesticides now in use should receive the greatest attention to safeguard the public health. The presented method uses a hazard to ground-water hydrogeological screening model (DRASTIC) and employs a one-dimensional pesticide transport model (CMLS). The method is an efficient and practical technique to identify where particular combinations of pesticides, water management practices, soils, and geology result in the greatest potential hazard to ground-water contamination. Use of the presented approach can reduce sampling needs and expense.
Water Resources Research, 1999
... Optimal design of aquifer cleanup systems under uncertainty using a neural network and a gene... more ... Optimal design of aquifer cleanup systems under uncertainty using a neural network and a genetic algorithm. Alaa H. Aly. Utah State University Research Foundation, Logan. Richard C. Peralta. Department of Biological and Irrigation Engineering, Utah State University, Logan. ...
Journal of Water Resources Planning and Management-asce, 2008
ABSTRACT Powerful simulation/optimization (S/O) models exist for designing groundwater well syste... more ABSTRACT Powerful simulation/optimization (S/O) models exist for designing groundwater well systems and pumping strategies. However, it can be challenging to use S/O modeling effectively for large, complex, and computationally intensive problems within project time and cost constraints. Here, we present a generic two-stage optimization procedure for making S/O modeling more practical. Application is illustrated for developing optimal transient 30-year pump-and-treat designs for Blaine Naval Ammunition Depot (NAD), Nebraska, and using an innovative hybrid advanced genetic algorithm with tabu search features (AGT). AGT includes standard genetic algorithm and tabu search features plus healing, elitism, threshold acceptance, and a new subset/subspace decomposition optimization. The screening stage simplifies the optimization problem, and selects desirable remediation wells from among many candidates. During this stage, computational effort is lessened by reducing the number of state variables needing evaluation, and the solution space dimensionality (including temporal dimensions). Subset/subspace decomposition optimization of steady flow rates is used to identify desirable sets of candidate wells. The transient optimization stage develops mathematically optimal time-varying pumping rates for well subsets identified by the screening stage. It also includes reoptimization using the original objective function plus goal programming to increase strategy robustness. Initializing the AGT with feasible solutions reduces computational effort. Within a short period the procedure developed optimal pump and treat system designs for NAD. The procedure yields better objective function values than trial and error. Because optimization causes tight constraints, the computed strategy is sensitive to changes in model parameters. Increasing strategy robustness via AGT and goal programming degrades the value of the initial objective function.
Journal of Water Resources Planning and Management-asce, 1990
Las opiniones vertidas en los artículos y notas de la revista reflejan el pensamiento de sus resp... more Las opiniones vertidas en los artículos y notas de la revista reflejan el pensamiento de sus respectivos autores y no necesariamente el del cuerpo editorial de Theologika.
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Papers by Richard Peralta