Browsing by Autor "Santiago Morales"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item type: Item ,
    An Exact Method for Reliable Shortest Path Problems With Correlation
    (Wiley, 2026) Esteban Leiva; Santiago Morales; Daniel Yamín; Andrés L. Medaglia
    ABSTRACT Shortest path problems often arise in contexts where travel times are uncertain. In these settings, reliable paths are often valued more than paths with lower expected travel times. This has led to several variants of reliable shortest path problems (RSPP) that handle travel time reliability differently. We propose an algorithmic framework for solving RSPPs with non‐negatively correlated travel times and resource constraints. By building upon the flexibility of the pulse algorithm, our unified and exact algorithmic framework solves multiple variants of the RSPP: the ‐reliable shortest path (‐RSP), the maximum probability of on‐time arrival (MPOAP) problem, and the shortest ‐reliable path (S‐). We derive a bound on the reliability of path travel times and incorporate three pruning strategies: bounds, infeasibility, and dominance, leveraging properties of the normal distribution and non‐negative correlation structures. Computational experiments on large‐scale transportation networks (with up to 33 113 nodes and 75 379 arcs) demonstrate that the framework achieves a ten‐fold speed improvement over state‐of‐the‐art methods, highlighting its potential real‐world applications and extensions to related problems.
  • Thumbnail Image
    Item type: Item ,
    Treatment Performance of Wastewater Lagoons in South Yungas Province of Bolivia
    (2009) Helen E. Muga; James R. Mihelcic; Nathan W. Reents; Santiago Morales; Gabriela Gemio; Meredith M. Ballard; Valerie J. Fuchs; Cara M. Hanson; Esther M. Johnson; Alison M. Hoyt
    The operation of wastewater lagoons systems located in the South Yungas Province of Bolivia has been analyzed over a 2-year period. Facultative and maturation lagoons were evaluated for their performance in removing total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrogen, phosphorus, and coliforms. Facultative lagoons operating in San Antonio were found to remove approximately 74% total suspended solids, 70–89% BOD, 62–85% COD, 53% nitrogen, 52% phosphorus and 97.8–99.9% coliforms. Maturation ponds were found to remove 74–93% total suspended solids, 22–62% BOD, 10–95% COD, 3% nitrogen, 20–95% phosphorus and 77.4–99.96% coliforms. Results from the 2-year study indicate that these wastewater treatment systems are currently performing as expected; however regular maintenance, specifically removing algae every (2 weeks) is required. The removal percentages of the treatment systems (comparing influent to effluent) ranged from 74–97% TSS, 78–98% BOD, 70–99.7% COD, 58–77% nitrogen, 62–99.9% phosphorus, and 99.99% coliforms.