Departamento de Ingenierías de la Industria y el Ambiente
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Item A study of cooling rate of the supercooled water inside of cylindrical capsules(Scopus, 2009) Braga, Sergio; Milón Guzmán, Juan José; Jiménez Pacheco, HugoAn experimental apparatus was developed to investigate the supercooling phenomenon of pure water inside cylindrical capsules used for cold storage process. The Phase Change Material (PCM) used was distilled water. The external coolant material was a water-alcohol mixture (50% vol.), controlled by a constant temperature bath (CTB) in four fixed values (-4 °C, -6 °C, -8 °C, and -10 °C). Temperatures varying with time were measured inside and outside the capsule. Cylindrical capsules with internal diameter of 30 mm, 45 mm, and 80 mm, with 1.5 mm wall thickness were made in aluminum, bronze or acrylic materials. The Cooling Rate (CR) was investigated for different positions on the internal wall of the capsule, for different external coolant temperatures (Tc), different capsules diameters and different materials. The results showed that the cooling rate is a strong function of the angular position on the internal wall, the coolant temperature, the capsule material, and the capsule's diameter. © 2008 Elsevier Ltd and IIR.Item Combined treatment based on synergism between hydrodynamic cavitation and H2O2 for degradation of cyanide in effluents(Elsevier Ltd, 2021) Montalvo Andia J.P, J.P.; Ticona Cayte, A.E.B.; Illachura Rodriguez, J.M.B.; López Belón, L.A.; Cárdenas Málaga M.A.b, M.A.B.; Teixeira, L.A.C."The main purpose of this research has been to evaluate and optimize the application of hydrodynamic cavitation (HC), combined with hydrogen peroxide, as a promising process for the effective degradation of cyanide in aqueous effluents. The experimental work was carried out using cavitation equipment with a venturi device connected to a tubular circuit which allowed a closed-cycle flow to run for 120 min, in which the effect of control parameters as inlet pressure, H2O2:CN─ ratio, pH, and temperature have been evaluated for the treatment of solutions with initial cyanide concentration in range 100 to 550 mg L─1. The results showed that in optimal conditions cyanide degradation using only HC reached 70% and, using solely H2O2 as oxidizing agent it reached 63%. Efficiency of the combined treatment process was evaluated on the basis of their synergetic effect as it turned out to be more effective showing a 99.9 % cyanide degradation in less than 120 min. The optimum set of conditions that produced the highest degradation rate and efficiency was: inlet pressure 4 bar; pH 9.5; and H2O2:CN─ ratio = 1.5:1. The process was also evaluated on the basis of cavitational yield and in terms of energy and chemical treatment costs. The results have demonstrated that the combined treatment technology of HC + H2O2 can be effectively used as a fast and highly efficient treatment of wastewater containing cyanide."Item Distribution patterns, ecological niche and conservation status of endemic Tillandsia purpurea along the Peruvian coast(Springer, 2021) Villasante Benavides;, Francisco; Pauca-Tanco, G. Anthony; Luque-Fernández, C. R.; Quispe-Turpo, Johana del Pilar; Villegas Paredes, Luis N.; Siegmund, Alexander; Koch, Marcus A.Species distribution modeling and assessment of the possible current conservation status for loma-forming Tillandsia purpurea Ruiz & Pavón in Peru were performed. This species is considered an epiarenic species that lives under hyperarid conditions, where its main source of water and nutrients comes from the fog of the Pacific coast. For the distribution modeling, 63 records from different sources of information were used, including a current field survey. Locations covered the whole range of the species´ known distribution along the Peruvian coast, and respective elevations lie between 0 and 2000 m a. s. l. Likewise, 27 environmental variables were used, including bioclimatic and eco-geographical ones, to determine the corresponding ecological niche and compare between actual and potential distribution. The conservation status was estimated according to the criteria recommended by the IUCN red list. High probability values were obtained predicting the occurrence of T. purpurea and describing respective environmental conditions such as altitudinal distribution between 400 and 1200 m and predominant southwest exposure of habitats. The conservation status of T. purpurea was supposed between "least concern" and near threatened, recommending that this species should be placed into the latter category and considering recurrent threats by direct anthropogenic impact and climate change verified during the field surveys.Item Geographic distribution and conservation status of Eulychnia ritteri Cullmann (Cactaceae), an endemic cactus from southern Peru(Facultad de Ciencias Biologicas, Universidad Nacional Mayor de San Marcos, 2021) Pauca-Tanco, G.A.; Balvin, M.; Hoxey, P.; Quipuscoa, V.; Quispe-Turpo, J.D.P.Eulychnia ritteri is endemic to Peru, restricted to the northern coast of the department of Arequipa. The lack of knowledge of this species, and threats such as human activities and climate change, put the populations at risk. In this research, we examined the geographical distribution and conservation status of E. ritteri in the coastal area of the Caravelí province. In addition, the population structure and phenology in the Quebrada Vizcachani population were evaluated using plots of 10×100 m. Data on the accompanying flora and local fauna were also obtained. Eulychnia ritteri showed five populations distributed from 15°43' to 15°47'S, with a total area of 63.62 ha (0.63 km2). The Quebrada Vizcachani population is the largest (24.5 ha) and the Cementerio population the smallest (0.018 ha). The population density evaluated is 0.06 ind/m2, where seedlings, juveniles, adults, and dead plants were 3.61, 24.09, 56.63 and 15.67% respectively. The phenology was asynchronous, the flower buds, flowers and fruits appear in the same period. The flowers and fruits were food for insects and rodents respectively, and 18 accompanying species have been recorded. Finally, E. ritteri is categorised as endangered (EN), given its geographical distribution and identified threats. © Los autoresItem Supercooling water in cylindrical capsules(Scopus, 2005) Milón Guzmán, Juan José; Braga, SergioAn experimental apparatus was developed to investigate the supercooling phenomenon of water inside cylindrical capsules used for a cold storage process. The coolant is a water-alcohol mixture controlled by a constant temperature bath (CTB). Temperatures varying with time are measured inside and outside the capsule. Cylinders with an internal diameter and thickness of 45 and 1.5mm, respectively, were made from four different materials: acrylic, PVC, brass, and aluminum. The supercooling period of the water and the nucleation temperature were investigated for different coolant temperatures. The supercooling and nucleation probabilities are shown as a function of the coolant temperature for the four different materials. © 2005 Springer Science+Business Media, Inc.Item The reversibility property in a job-insertion tiebreaker for the permutational flow shop scheduling problem(Elsevier B.V., 2021) Benavides, A.J.; Vera, A.The best performing approximate methods proposed for the permutational flow shop scheduling problem with makespan minimization are the well known NEH constructive heuristic and the iterated greedy algorithm. Both methods are based on the successive insertion (or reinsertion) of jobs into a partial schedule, evaluating the makespan of the resulting schedule for all insertion positions, and selecting the insertion position that presents the shortest makespan. Frequently, there are many tied insertion positions that produce such shortest makespan. Thus, a tiebreaker must be used to discern a selection among the tied insertion positions. Many tiebreakers have been proposed in the literature for this case. These tiebreakers improve the results produced by approximate methods when embedded into them. In this paper we propose two new tiebreakers that use a weighted and an unweighted approximation of the idle time increment produced by inserting the job into each tied insertion position. They were designed considering the reversibility property of the PFSSP. Our computational experiments show that the proposed tiebreakers outperform tiebreakers from the literature when evaluated within the NEH heuristic and within the iterated greedy algorithm. The iterated greedy algorithms with the proposed tiebreakers embedded are the best approximate methods so far for the permutational flow shop scheduling problemItem The reversibility property in a job-insertion tiebreaker for the permutational flow shop scheduling problem(Universidad Católica San Pablo, 2024) Vera Villegas, Antony Hector; Benavides Rojas, Alexander JavierThe best performing approximate methods proposed for the permutational flow shop scheduling problem with makespan minimization are the well known NEH constructive heuristic and the iterated greedy algorithm. Both methods are based on the successive insertion (or reinsertion) of jobs into a partial schedule, evaluating the makespan of the resulting schedule for all insertion positions, and selecting the insertion position that presents the shortest makespan. Frequently, there are many tied insertion positions that produce such shortest makespan. Thus, a tiebreaker must be used to discern a selection among the tied insertion positions. Many tiebreakers have been proposed in the literature for this case. These tiebreakers improve the results produced by approximate methods when embedded into them. In this paper we propose two new tiebreakers that use a weighted and an unweighted approximation of the idle time increment produced by inserting the job into each tied insertion position. They were designed considering the reversibility property of the PFSSP. Our computational experiments show that the proposed tiebreakers outperform tiebreakers from the literature when evaluated within the NEH heuristic and within the iterated greedy algorithm. The iterated greedy algorithms with the proposed tiebreakers embedded are the best approximate methods so far for the permutational flow shop scheduling problem.Item Visualization of dendritic ice growth in supercooled water inside cylindrical capsules(Scopus, 2012) Braga, Sergio; Milón Guzmán, Juan JoséAn experimental device was developed to study dendritic ice growth in supercooled water inside cylindrical capsules. The capsule materials investigated were acrylic, PVC (polyvinyl chloride), bronze and aluminum. The internal diameter of all the capsules was 45 mm. The results indicate that dendritic ice appears only in supercooled water at the start of nucleation. Blockage by dendritic ice growth was classified according to the capsule material and the coolant temperature. Total blockage (100%) and partial blockage (25%, 50% and 75%) was observed. Dendritic ice growth was shown and analyzed in photographic sequences. © 2012 Elsevier Ltd. All rights reserved.