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Author Osorio-Valenzuela, L.; Pereira, J.; Quezada, F.; Vasquez, O.C. doi  openurl
  Title Minimizing the number of machines with limited workload capacity for scheduling jobs with interval constraints Type Journal Article
  Year 2019 Publication Applied Mathematical Modelling Abbreviated Journal Appl. Math. Model.  
  Volume 74 Issue Pages 512-527  
  Keywords Scheduling; Parallel machines; Interval and workload constraints; Branch-and-price  
  Abstract In this paper, we consider a parallel machine scheduling problem in which machines have a limited workload capacity and jobs have deadlines and release dates. The problem is motivated by the operation of energy storage management systems for microgrids under emergency conditions and generalizes some problems that have already been studied in the literature for their theoretical value. In this work, we propose heuristic and exact algorithms to solve the problem. The heuristics are adaptations of classical bin packing heuristics in which additional conditions on the feasibility of a solution are imposed, whereas the exact method is a branch-and-price approach. The results show that the branch-andprice approach is able to optimally solve random instances with up to 250 jobs within a time limit of one hour, while the heuristic procedures provide near optimal solution within reduced running times. Finally, we also provide additional complexity results for a special case of the problem. (C) 2019 Elsevier Inc. All rights reserved.  
  Address [Osorio-Valenzuela, Luis] Univ Santiago Chile, Elect Engn Dept, Santiago, Chile, Email: luis.osoriov@usach.cl;  
  Corporate Author Thesis  
  Publisher Elsevier Science Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0307-904x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000474317800031 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1013  
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Author Owerre, S.A.; Mellado, P.; Baskaran, G. doi  openurl
  Title Photoinduced Floquet topological magnons in Kitaev magnets Type Journal Article
  Year 2019 Publication Epl Abbreviated Journal Epl  
  Volume 126 Issue 2 Pages 7 pp  
  Keywords  
  Abstract We study periodically driven pure Kitaev model and ferromagnetic phase of the Kitaev-Heisenberg model on the honeycomb lattice by off-resonant linearly and circularly polarized lights at zero magnetic field. Using a combination of linear spin wave and Floquet theories, we show that the effective time-independent Hamiltonians in the off-resonant regime map onto the corresponding anisotropic static spin model, plus a tunable photoinduced magnetic field along the [111] direction, which precipitates Floquet topological magnons and chiral magnon edge modes. They are tunable by the light amplitude and polarization. Similarly, we show that the thermal Hall effect induced by the Berry curvature of the Floquet topological magnons can also be tuned by the laser field. Our results pave the way for ultrafast manipulation of topological magnons in irradiated Kitaev magnets, and could play a pivotal role in the investigation of ultrafast magnon spin current generation in Kitaev materials. Copyright (C) EPLA, 2019  
  Address [Owerre, S. A.; Mellado, Paula; Baskaran, G.] Perimeter Inst Theoret Phys, 31 Caroline St N, Waterloo, ON N2L 2Y5, Canada, Email: sowerre@perimeterinstitute.ca  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0295-5075 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000469803300001 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1032  
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Author Pabon-Pereira, C.; Slingerland, M.; Hogervorst, S.; van Lier, J.; Rabbinge, R. pdf  doi
openurl 
  Title A Sustainability Assessment of Bioethanol (EtOH) Production: The Case of Cassava in Colombia Type Journal Article
  Year 2019 Publication Sustainability Abbreviated Journal Sustainability  
  Volume 11 Issue 14 Pages 23 pp  
  Keywords cassava; bioethanol; energy crops; sustainability analysis; biofuels; bioenergy production  
  Abstract This paper shows how system design determines sustainability outcomes of cassava bioethanol production in Colombia. The recovery of the energy contained in by-products is recommended as compared to single product production. In particular, this study assesses the energy, greenhouse gases, water, and land use performance of alternative cassava cascades working at different scales, highlighting the implications of including anaerobic digestion technology in the chain. The centralized systems showed a poorer energy and greenhouse gases performance as compared to decentralized ones in part due to the artificial drying of cassava chips in the centralized facility. Under solar drying of cassava chips, systems with anaerobic digestion produced three to five times more energy than demanded and produced greenhouse gas savings of 0.3 kgCO(2eq) L EtOH-1. The water balance output depends upon the water reuse within the ethanol industry, which demands 21-23 L EtOH-1. In the anaerobic digestion scenarios, assuming liquid flows are treated separately, complete water recovery is feasible. Land use for cassava cultivation was calculated to be 0.27-0.35 ha tEtOH(-1). The energy and water content of the material to digest, the options for digestate reuse, and the recovery of the methane produced are major considerations substantially influencing the role of anaerobic digestion within cassava cascade configurations.  
  Address [Pabon-Pereira, Claudia] Univ Adolfo Ibanez, Fac Engn & Sci, Santiago 7910000, Chile, Email: claudia.pabon@uai.cl  
  Corporate Author Thesis  
  Publisher Mdpi Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2071-1050 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000482261800212 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1050  
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Author Palmeiro-Sanchez, T.; del Rio, A.V.; Fra-Vazquez, A.; Campos, J.L.; Mosquera-Corral, A. doi  openurl
  Title High -Yield Synthesis of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Copolymers in a Mixed Microbial Culture: Effect of Substrate Switching and F/M Ratio Type Journal Article
  Year 2019 Publication Industrial & Engineering Chemistry Research Abbreviated Journal Ind. Eng. Chem. Res.  
  Volume 58 Issue 48 Pages 21921-21926  
  Keywords  
  Abstract The accumulation capacity of a mixed microbial culture (MMC) is affected if the substrate used in the accumulation experiments differs from the one used in the enrichment. For this reason, the effect of substrate switching was studied to determine the versatility of an MMC enriched in a mixture of volatile fatty acids (VFA(max)) to overcome this problem. The MMC was enriched using a VFA(max) composed of 48.3:24.3:7.3:14.7 CmM acetic (HAc), propionic (HPr), butyric (HBu), and valeric (HVa) acids, respectively. The accumulation capacity was tested using single VFAs (HAc, HPr, HBu, and HVa), as well as the VFA,Um used in the enrichment. The accumulation capacities were 52.8 +/- 4.7, 48.8 +/- 4.3, 45.2 3.0, 48.4 +/- 1.0, and 54.5 +/- 8.0 wt% for HAc, HPr, HBu, HVa, and rVFA(max) espectively, with polymer compositions of 50.6 15.1, 0.4 0.1, 63.2 1.5, 0.3 0.0, and 2.0 0.7 g 3-HB/g 3-14V, following the same order. The average yields were 0.84 0.08, 0.76 +/- 0.09, 0.74 0.02, 0.70 +/- 0.01, and 0.68 +/- 0.09 CmolpHA/CmolvF, for HVa, VFAmX, HAc, HBu, and HPr, respectively. The feed -to -microorganism (F/M) ratio showed that values of 1-7 CmolvFA/(Cmolx) in the accumulation experiments led to the optimal yields. Based on the results obtained, it seems feasible to enrich an MMC able to produce tailormade biopolymers from different VFAs at high yields.  
  Address [Palmeiro-Sanchez, Tania] Natl Univ Ireland Galway, Sch Nat Sci, Microbiol, Galway H91 TK33, Ireland, Email: tania.palmeirosanchez@nuigalway.ie  
  Corporate Author Thesis  
  Publisher Amer Chemical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0888-5885 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000501621800004 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1071  
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Author Parra, P.F.; Arteta, C.A.; Moehle, J.P. pdf  doi
openurl 
  Title Modeling criteria of older non-ductile concrete frame-wall buildings Type Journal Article
  Year 2019 Publication Bulletin Of Earthquake Engineering Abbreviated Journal Bull. Earthq. Eng.  
  Volume 17 Issue 12 Pages 6591-6620  
  Keywords Non-ductile buildings; Nonlinear analysis; Plastic collapse mechanism; Base shear strength; Hazard levels  
  Abstract The purpose of seismic provisions included in modern building codes is to obtain a satisfactory structural performance of buildings during earthquakes. However, in the United States and elsewhere, there are large inventories of buildings designed and constructed several decades ago, under outdated building codes. Some of these buildings are classified as non-ductile buildings. Currently, under the ATC-78 project, a methodology is being developed to identify seismically hazardous frame-wall buildings through a simple procedure that does not require full nonlinear analyses by the responsible engineer. This methodology requires the determination of the controlling plastic collapse mechanism, the base shear strength, and the ratio between the story drift ratio and the roof drift ratio, called parameter alpha, at collapse level. The procedure is calibrated with fully inelastic nonlinear analyses of archetype buildings. In this paper we first introduce an efficient scheme for modeling frame-wall buildings using the software OpenSees. Later, the plastic collapse mechanism, the base shear strength, and values of alpha are estimated from nonlinear static and dynamic analyses considering a large suite of ground-motion records that represent increasing hazard levels. The analytical experiment included several frame-wall combinations in 4 and 8-story buildings, intended to represent a broad range of conditions that can be found in actual buildings, where the simplified methodology to evaluate the risk of collapse can be applicable. Analysis results indicate that even walls of modest length may positively modify the collapse mechanism of nonductile bare frames preventing soft story failures.  
  Address [Parra, P. F.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Diagonal Las Torres 2700, Santiago, Chile, Email: pablo.parra@uai.cl  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1570-761x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000496337400011 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1072  
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Author Pichel, A.; Moreno, R.; Figueroa, M.; Campos, J.L.; Mendez, R.; Mosquera-Corral, A.; del Rio, A.V. doi  openurl
  Title How to cope with NOB activity and pig manure inhibition in a partial nitritation-anammox process? Type Journal Article
  Year 2019 Publication Separation And Purification Technology Abbreviated Journal Sep. Purif. Technol.  
  Volume 212 Issue Pages 396-404  
  Keywords Anammox; Pig manure; Inhibition; Nitrite oxidizers (NOB); Dissolved oxygen control  
  Abstract The treatment of pig manure can be performed by anaerobic digestion to diminish the organic matter content and produce biogas, and the resulting digestate has to be subsequently treated for the removal of nitrogenous compounds. The partial nitritation-anammox (PN-AMX) process constitutes an interesting alternative. In the present study, three different short experiments were initially performed to study the influence of nitrite oxidizing bacteria (NOB) present in the inoculum and the pig manure composition over the start-up of the PN-AMX process. The presence of NOB in the inoculum showed to be more crucial than the available anammox activity for a good performance of the PN-AMX process. Batch activity experiments showed a reduction of at least 44.4% in the maximum specific anammox activity due to the pig manure, probably owed to its conductivity (between 6 and 8 mS/cm). In the subsequent long-term operation of the PN-AMX process with non-diluted pre-treated pig manure, the NOB were successfully limited for DO concentrations of 0.1 mg O-2/L, and a nitrogen removal rate (NRR) of 0.1 g N/(L.d) was achieved despite the presence of significant NOB activity in the start-up. A strict control of the DO concentration, with an optimal range of 0.07-0.10 mg O-2/L, was fundamental to balance the removal of nitrogen by PN-AMX and prevent NOB activity. The presence of organic matter, with a ratio sCOD/N in the influent between 0.18 and 1.14 g/g, did not hinder the PN-AMX process, and the contribution of heterotrophic denitrification to the removal of nitrogen was less than 10%.  
  Address [Pichel, Andres; Figueroa, Monica; Mendez, Ramon; Mosquera-Corral, Anuska; Val del Rio, Angeles] Univ Santiago de Compostela, Sch Engn, Dept Chem Engn, E-15705 Santiago De Compostela, Spain, Email: andres.gutierrez.pichel@usc.es  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1383-5866 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000457814700044 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1039  
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Author Rademaker, L.; Abanin, D.A.; Mellado, P. doi  openurl
  Title Charge smoothening and band flattening due to Hartree corrections in twisted bilayer graphene Type Journal Article
  Year 2019 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 100 Issue 20 Pages 6 pp  
  Keywords  
  Abstract Doping twisted bilayer graphene away from charge neutrality leads to an enormous buildup of charge inhomogeneities within each moire unit cell. Here, we show, using unbiased real-space self-consistent Hartree calculations on a relaxed lattice, that Coulomb interactions smoothen this charge imbalance by changing the occupation of earlier identified “ring” orbitals in the AB/BA region and “center” orbitals at the AA region. For hole doping, this implies an increase of the energy of the states at the Gamma point, leading to a further flattening of the flat bands and a pinning of the Van Hove singularity at the Fermi level. The charge smoothening will affect the subtle competition between different possible correlated phases.  
  Address [Rademaker, Louk; Abanin, Dmitry A.] Univ Geneva, Dept Theoret Phys, CH-1211 Geneva, Switzerland  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9950 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000495966000004 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1074  
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Author Ramajo, L.; Fernandez, C.; Nunez, Y.; Caballero, P.; Lardies, M.A.; Poupin, M.J. pdf  doi
openurl 
  Title Physiological responses of juvenile Chilean scallops (Argopecten purpuratus) to isolated and combined environmental drivers of coastal upwelling Type Journal Article
  Year 2019 Publication Ices Journal Of Marine Science Abbreviated Journal ICES J. Mar. Sci.  
  Volume 76 Issue 6 Pages 1836-1849  
  Keywords environmental drivers; environmental heterogeneity; global change; metabolism; multi-stressor; physiology; tolerance; upwelling  
  Abstract Coastal biota is exposed to continuous environmental variability as a consequence of natural and anthropogenic processes. Responding to heterogeneous conditions requires the presence of physiological strategies to cope with the environment. Ecosystems influenced by upwelling endure naturally cold, acidic and hypoxic conditions, nevertheless they sustain major fisheries worldwide. This suggests that species inhabiting upwelling habitats possess physiological adaptations to handle high environmental variability. Here, we assessed the impact of the main upwelling drivers (temperature, pH and oxygen) in isolation and combined on eco-physiological responses of Chilean scallop Argopecten purpuratus. A. purpuratus responded to hypoxia by increasing their metabolic performance to maintain growth and calcification. Calcification was only affected by pH and increased under acidic conditions. Further, A. purpuratus juveniles prioritized calcification at the expense of growth under upwelling conditions. Increasing temperature had a significant impact by enhancing the physiological performance of A. purpuratus juveniles independently of oxygen and pH conditions, but this was associated with earlier and higher mortalities. Our results suggest that A. purpuratus is acclimated to short-term colder, acidic and hypoxic conditions, and provide important information of how this species responds to the heterogeneous environment of upwelling, which is significantly relevant in the climatic context of upwelling intensification.  
  Address [Ramajo, Laura; Fernandez, Carolina; Lardies, Marco A.] Univ Adolfo Ibanez, Fac Artes Liberales, Dept Ciencias, Ave Diagonal Las Torres 2640, Santiago, Chile, Email: laura.ramajo@ceaza.cl  
  Corporate Author Thesis  
  Publisher Oxford Univ Press Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1054-3139 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000501732500040 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1068  
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Author Ramirez-Flandes, S.; Gonzalez, B.; Ulloa, O. doi  openurl
  Title Redox traits characterize the organization of global microbial communities Type Journal Article
  Year 2019 Publication Proceedings Of The National Academy Of Sciences Of The United States Of America Abbreviated Journal Proc. Natl. Acad. Sci. U. S. A.  
  Volume 116 Issue 9 Pages 3630-3635  
  Keywords microbial ecology; functional traits; oxidoreductases; biomes; metagenomics  
  Abstract The structure of biological communities is conventionally described as profiles of taxonomic units, whose ecological functions are assumed to be known or, at least, predictable. In environmental microbiology, however, the functions of a majority of microorganisms are unknown and expected to be highly dynamic and collectively redundant, obscuring the link between taxonomic structure and ecosystem functioning. Although genetic trait-based approaches at the community level might overcome this problem, no obvious choice of gene categories can be identified as appropriate descriptive units in a general ecological context. We used 247 microbial metagenomes from 18 biomes to determine which set of genes better characterizes the differences among biomes on the global scale. We show that profiles of oxidoreductase genes support the highest biome differentiation compared with profiles of other categories of enzymes, general protein-coding genes, transporter genes, and taxonomic gene markers. Based on oxidoreductases' description of microbial communities, the role of energetics in differentiation and particular ecosystem function of different biomes become readily apparent. We also show that taxonomic diversity is decoupled from functional diversity, e. g., grasslands and rhizospheres were the most diverse biomes in oxidoreductases but not in taxonomy. Considering that microbes underpin biogeochemical processes and nutrient recycling through oxidoreductases, this functional diversity should be relevant for a better understanding of the stability and conservation of biomes. Consequently, this approach might help to quantify the impact of environmental stressors on microbial ecosystems in the context of the global-scale biome crisis that our planet currently faces.  
  Address [Ramirez-Flandes, Salvador; Ulloa, Osvaldo] Univ Concepcion, Dept Oceanog, Concepcion 4070386, Chile, Email: sram@udec.cl;  
  Corporate Author Thesis  
  Publisher Natl Acad Sciences Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0027-8424 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000459694400048 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 985  
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Author Ramirez-Morales, J.E.; Tapia-Venegas, E.; Campos, J.L.; Ruiz-Filippi, G. doi  openurl
  Title Operational behavior of a hydrogen extractive membrane bioreactor (HEMB) during mixed culture acidogenic fermentation Type Journal Article
  Year 2019 Publication International Journal Of Hydrogen Energy Abbreviated Journal Int. J. Hydrog. Energy  
  Volume 44 Issue 47 Pages 25565-25574  
  Keywords Biohydrogen separation; Fermentative hydrogen upgrading; Hydrogen partial pressure; Polymeric membrane; Gas extractive fermentation  
  Abstract Fermentative hydrogen production requires a continuous products-removal and effective upgrading steps to improve its general performance. Therefore, implementation of new technologies capable of achieving both requirements is essential. We present the operational behavior of a new process concept based on integration of membranes for gas separation and fermentation technology. This process, which we term as hydrogen extractive membrane bioreactor consists of coupling two dense polymeric membranes to a hydrogen producing culture. The process automatization of this system was essential to maintain the proper operational pressures in the membrane module and in the bioreactorgas-phase. This system was able to extract and partially separate the hydrogen and carbon dioxide generated. The hydrogen partial pressure was reduced from 55.5 to 49 KPa, which means an increase of hydrogen yield of 16.3% (1.1-1.28 mol-H-2/mol-glucose). Simultaneously, the implemented system generated a final hydrogen stream 13% (v/v) more concentrated than a conventional process. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.  
  Address [Ramirez-Morales, Juan E.; Tapia-Venegas, Estela; Ruiz-Filippi, Gonzalo] Pontificia Univ Catolica Valparaiso, Escuela Ingn Bioquim, Av Brasil 2085, Valparaiso 2340950, Chile, Email: juan.ramirez@rwth-aachen.de  
  Corporate Author Thesis  
  Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0360-3199 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000490030000022 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1090  
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Author Ramirez-Sagner, G.; Munoz, F.D. doi  openurl
  Title The effect of head-sensitive hydropower approximations on investments and operations in planning models for policy analysis Type Journal Article
  Year 2019 Publication Renewable & Sustainable Energy Reviews Abbreviated Journal Renew. Sust. Energ. Rev.  
  Volume 105 Issue Pages 38-47  
  Keywords Generation planning; Hydropower; Policy analysis; Simplifications; Uncertainty  
  Abstract Planning for new generation infrastructure in hydrothermal power systems requires consideration of a series of nonlinearities that are often ignored in planning models for policy analysis. In this article, three different capacity- planning models are used, one nonlinear and two linear ones, with different degrees of complexity, to quantify the impact of simplifying the head dependency of hydropower generation on investments in both conventional and renewable generators and system operations. It was found that simplified investment models can bias the optimal generation portfolios by, for example, understating the need for coal and combined-cycle gas units and overstating investments in wind capacity with respect to a more accurate nonlinear formulation, which could affect policy recommendations. It was also found that the economic cost of employing a simplified model can be below 10% of total system cost for most of the scenarios and system configurations analyzed, but as high as nearly 70% of total system cost for specific applications. Although these results are not general, they suggest that for certain system configurations both linear models can provide reasonable approximations to more complex nonlinear formulations. Uncertain water inflows were also considered using stochastic variants of all three planning models. Interestingly, if due to time or computational limitations only one of these two features could be accounted for, these results indicate that explicit modeling of the nonlinear-head effect in a deterministic model could yield better results (up to 0.6% of economic regret) than a stochastic linear model (up to 9.6% of economic regret) that considers the uncertainty of water inflows.  
  Address [Ramirez-Sagner, Gonzalo] Fraunhofer Chile Res, Ctr Solar Energy Technol, Santiago, Chile, Email: grramire@uc.cl;  
  Corporate Author Thesis  
  Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1364-0321 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000460121000003 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 988  
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Author Reus, L. doi  openurl
  Title Currency risk in foreign currency accounts for small and medium-sized businesses Type Journal Article
  Year 2019 Publication Journal of Risk Abbreviated Journal J. Risk  
  Volume 22 Issue 2 Pages 59-78  
  Keywords  
  Abstract This paper estimates the currency exposure before and after the hedging of active foreign currency (FC) accounts, using stochastic models for spot exchange rates and cashflow movements. It examines a simple hedging policy that is typically applied by small and medium-sized businesses that do not have the expertise or resources to execute sophisticated strategies. The performance of the policy is measured through the derivation of analytical expressions for its profit and loss (P&L): that is, the earnings resulting from the valuation of the FC accounts and of the forward contracts taken. The results for five currencies show that the policy reduces P&L volatility compared with that for an unhedged account, without necessarily reducing the mean P&L. The mean and volatility of the P&L are not sensitive to the maturity of the contracts, and the volatility is almost linearly related to the currency volatility.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1465-1211 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1084  
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Author Reus, L.; Pagnoncelli, B.; Armstrong, M. doi  openurl
  Title Better management of production incidents in mining using multistage stochastic optimization Type Journal Article
  Year 2019 Publication Resources Policy Abbreviated Journal Resour. Policy  
  Volume 63 Issue Pages 13 pp  
  Keywords Mining incidents; Optimal policy; Stochastic dual dynamic programming; Risk-aversion; CVaR; Julia language  
  Abstract Among the many sources of uncertainty in mining are production incidents: these can be strikes, environmental issues, accidents, or any kind of event that disrupts production. In this work, we present a strategic mine planning model that takes into account these types of incidents, as well as random prices. When confronted by production difficulties, mines which have contracts to supply customers have a range of flexibility options including buying on the spot market, or taking material from a stockpile if they have one. Earlier work on this subject was limited in that the optimization could only be carried out for a few stages (up to 5 years) and in that it only analyzed the risk-neutral case. By using decomposition schemes, we are now able to solve large-scale versions of the model efficiently, with a horizon of up to 15 years. We consider decision trees with up to 615 scenarios and implement risk aversion using Conditional Value-at-Risk, thereby detecting its effect on the optimal policy. The results provide a “roadmap” for mine management as to optimal decisions, taking future possibilities into account. We present extensive numerical results using the new sddp.jl library, written in the Julia language, and discuss policy implications of our findings.  
  Address [Reus, Lorenzo] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago, Chile, Email: lorenzo.reus@uai.cl;  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0301-4207 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000488888100004 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1165  
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Author Rojas, E.R.; Dumais, J. doi  openurl
  Title A Mechanical Cusp Catastrophe Imposes a Universal Developmental Constraint on the Shapes of Tip-Growing Cells Type Abstract
  Year 2019 Publication Biophysical Journal Abbreviated Journal Biophys. J.  
  Volume 116 Issue 3 Pages 121A-121A  
  Keywords  
  Abstract  
  Address [Rojas, Enrique R.] NYU, Biol, New York, NY USA  
  Corporate Author Thesis  
  Publisher Cell Press Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0006-3495 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000460779800598 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 991  
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Author Rubio, C.A.; Asenjo, F.A.; Hojman, S.A. doi  openurl
  Title Quantum Cosmologies Under Geometrical Unification of Gravity and Dark Energy Type Journal Article
  Year 2019 Publication Symmetry-Basel Abbreviated Journal Symmetry  
  Volume 11 Issue 7 Pages  
  Keywords  
  Abstract A Friedmann-Robertson-Walker Universe was studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann-Robertson-Walker-quintessence (FRWq) system, was presented. It was shown that the classical Lagrangian reproduces the usual two (second order) dynamical equations for the radius of the Universe and for the quintessence scalar field, as well as a (first order) constraint equation. Our approach naturally unified gravity and dark energy, as it was obtained that the Lagrangian and the equations of motion are those of a relativistic particle moving on a two-dimensional, conformally flat spacetime. The conformal metric factor was related to the dark energy scalar field potential. We proceeded to quantize the system in three different schemes. First, we assumed the Universe was a spinless particle (as it is common in literature), obtaining a quantum theory for a Universe described by the Klein-Gordon equation. Second, we pushed the quantization scheme further, assuming the Universe as a Dirac particle, and therefore constructing its corresponding Dirac and Majorana theories. With the different theories, we calculated the expected values for the scale factor of the Universe. They depend on the type of quantization scheme used. The differences between the Dirac and Majorana schemes are highlighted here. The implications of the different quantization procedures are discussed. Finally, the possible consequences for a multiverse theory of the Dirac and Majorana quantized Universe are briefly considered.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2073-8994 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000481979000025 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1048  
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Author Sandford, E.; Espinoza, N.; Brahm, R.; Jordan, A. doi  openurl
  Title Estimation of singly transiting K2 planet periods with Gaia parallaxes Type Journal Article
  Year 2019 Publication Monthly Notices Of The Royal Astronomical Society Abbreviated Journal Mon. Not. Roy. Astron. Soc.  
  Volume 489 Issue 3 Pages 3149-3161  
  Keywords methods: data analysis; methods: statistical; planets and satellites: fundamental parameters; stars: planetary systems  
  Abstract When a planet is only observed to transit once, direct measurement of its period is impossible. It is possible, however, to constrain the periods of single transiters, and this is desirable as they are likely to represent the cold and far extremes of the planet population observed by any particular survey. Improving the accuracy with which the period of single transiters can be constrained is therefore critical to enhance the long-period planet yield of surveys. Here, we combine Gaia parallaxes with stellar models and broad-band photometry to estimate the stellar densities of K2 planet host stars, then use that stellar density information to model individual planet transits and infer the posterior period distribution. We show that the densities we infer are reliable by comparing with densities derived through asteroseismology, and apply our method to 27 validation planets of known (directly measured) period, treating each transit as if it were the only one, as well as to 12 true single transiters. When we treat eccentricity as a free parameter, we achieve a fractional period uncertainty over the true single transits of 94(-58)(+87) per cent, and when we fix e = 0, we achieve fractional period uncertainty 15(-6)(+30) per cent, a roughly threefold improvement over typical period uncertainties of previous studies.  
  Address [Sandford, Emily] Columbia Univ, Dept Astron, 550 W 120th St, New York, NY 10027 USA, Email: esandford@astro.columbia.edu  
  Corporate Author Thesis  
  Publisher Oxford Univ Press Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0035-8711 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000489288600015 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1088  
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Author Santana, L.E.; Canepa, G.H. doi  openurl
  Title Are they bots? Social media automation during Chile's 2017 presidential campaign Type Journal Article
  Year 2019 Publication Cuadernos Info Abbreviated Journal Cuad. Info  
  Volume Issue 44 Pages 61-77  
  Keywords bots; propaganda; elections; social media; democracy  
  Abstract This research sought for automated strategies of creation or diffusion of electoral propaganda in social media during Chile's 2017 presidential campaign. We collected and analyzed almost 2 million tweets that utilized election hashtags or were linked to one of the candidates or their campaigns; we also collected and analyzed 2,927 official Facebook posts of the candidates and 453,668 comments. While on Facebook the behavior was relatively normal, we discovered that on Twitter there were digital brigades who act autonomously in astroturfing campaigning during the first round of the election.  
  Address [Santana, Luis E.] Univ Adolfo Ibanez, Escuela Comunicac & Periodismo, Santiago, Chile, Email: luis.santana@uai.cl;  
  Corporate Author Thesis  
  Publisher Pontificia Univ Catolica Chile, Fac Comunicaciones Place of Publication Editor  
  Language Spanish Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0719-3661 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000471012200004 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1026  
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Author Sepulveda-Mardones, M.; Campos, J.L.; Magri, A.; Vidal, G. doi  openurl
  Title Moving forward in the use of aerobic granular sludge for municipal wastewater treatment: an overview Type Journal Article
  Year 2019 Publication Reviews In Environmental Science And Bio-Technology Abbreviated Journal Rev. Environ. Sci. Bio-Technol.  
  Volume 18 Issue 4 Pages 741-769  
  Keywords Aerobic granular sludge; Domestic sewage; Full-scale; Wastewater treatment plant  
  Abstract Activated sludge is one of the most widely implemented technologies for municipal wastewater treatment. Yet, more restrictive environmental standards demand for more efficient technologies. Aerobic granular sludge (AGS) is a promising alternative in this context since this technology has shown potential for simultaneous organic matter and nutrient removal using smaller bioreactors and consuming less energy. However, despite such engaging claims, only ca. 40 full-scale AGS systems have been installed worldwide after 30 years of development. This reduced implementation suggests the existence of significant bottlenecks for this technology, which currently only have partially been overcome. This overview aims to analyze the recent progress in R&D concerning aerobic sludge granulation for municipal wastewater treatment via the analysis of research articles and invention patents as well as to elucidate exiting technological gaps and development opportunities. Culturing methods aiming at fast granulation, long-term stability and excellent process performance are of utmost interest for promoting massive implementation of full-scale AGS systems. Moreover, the recovery of biomaterials from waste sludge could contribute to the implementation of the biorefinery paradigm in wastewater treatment plants.  
  Address [Sepulveda-Mardones, Mario; Vidal, Gladys] Univ Concepcion, Engn & Biotechnol Environm Grp, Environm Sci Fac, Concepcion, Chile, Email: glvidal@udec.cl  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1569-1705 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000490631800001 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1089  
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Author Silva-Oelker, G.; Jerez-Hanckes, C.; Fay, R. doi  openurl
  Title High-temperature tungsten-hafnia optimized selective thermal emitters for thermophotovoltaic applications Type Journal Article
  Year 2019 Publication Journal Of Quantitative Spectroscopy & Radiative Transfer Abbreviated Journal J. Quant. Spectrosc. Radiat. Transf.  
  Volume 231 Issue Pages 61-68  
  Keywords Thermophotovoltaics; Thermal emitters; Optimization; Surface plasmon polaritons; Fabry-Perot  
  Abstract Tungsten-hafnia (W-HfO2) selective thermal emitters with high hemispherical emittance for thermophotovoltaic (TPV) applications are explored through numerical simulations. Two structures were analyzed: a planar multilayer stack and a grating. In both cases, through suitable design choices high thermal emittance with low directional sensitivity can be obtained. The designs are obtained by optimization of the structures using a genetic algorithm and a suitable cost function, along with simulations of the structures' emittance by using rigorous coupled wave analysis. Calculations show that these optimized structures possess high hemispherical thermal emittance for the wavelength range that matches the optical response of GaSb photovoltaic cells. For each structure, both the output power from the TPV cell and the conversion efficiency are studied as a function of emitter temperature and physical understanding of the optimized structures is developed. (C) 2019 Elsevier Ltd. All rights reserved.  
  Address [Silva-Oelker, G.] Univ Tecnol Metropolitana, Dept Mech Engn, Av Jose Pedro Alessandri 1242, Nunoa, Region Metropol, Chile, Email: g.silva.o@utem.cl  
  Corporate Author Thesis  
  Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000469898100008 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 1019  
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Author Simon, F.; Ordonez, J.; Girard, A.; Parrado, C. doi  openurl
  Title Modelling energy use in residential buildings: How design decisions influence final energy performance in various Chilean climates Type Journal Article
  Year 2019 Publication Indoor And Built Environment Abbreviated Journal Indoor Built Environ.  
  Volume 28 Issue 4 Pages 533-551  
  Keywords Energy modelling; Building thermal performance; Parametric sensitivity analysis; Energy efficiency; CO2 emissions; Chile  
  Abstract To reduce the energy consumption in buildings, there is a demand for tools that identify significant parameters of energy performance. The work presents the development and validation of a simulation model, called MEEDI, and graphical figures for the parametric sensitivity investigation of energy performance in different climates in Chile. The MEEDI is based on the ISO 13790 monthly calculation method of building energy use with two improved procedures for the calculation of the heat transfer through the floor and the solar heat gains. The graphical figures illustrate the effects of climate conditions, envelope components and window size and orientation on the energy consumption. The MEEDI program can contribute to find the best solution to increase energy efficiency in residential buildings. It can be adapted for various parameters, making it useful for future projects. The economic viability of specific measures for building envelope materials was analysed. Payback periods range from 5 to 27 years depending on the location and energy scenario. The study illustrates how building design decisions can have a significant impact on final energy performance. With simple envelope components modification, valuable energy gains and carbon emission reductions can be achieved in a cost-effective manner in Chile.  
  Address [Simon, Francois; Ordonez, Javier; Parrado, Cristobal] Univ Granada, ETS Ingn Caminos Canales & Puertos, Dept Civil Engn, Granada, Spain, Email: fsimon730@gmail.com  
  Corporate Author Thesis  
  Publisher Sage Publications Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1420-326x ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000461388600009 Approved no  
  Call Number UAI @ eduardo.moreno @ Serial 992  
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