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Carrasco, M., Alvarez, F., Velazquez, R., Concha, J., & PerezCotapos, F. (2019). BrushHolder Integrated Load Sensor Prototype for SAG Grinding Mill Motor. Electronics, 8(11), 14 pp.
Abstract: One of the most widely used electromechanical systems in largescale mining is the electric motor. This device is employed in practically every phase of production. For this reason, it needs to be inspected regularly to maintain maximum operability, thus avoiding unplanned stoppages. In order to identify potential faults, regular checkups are performed to measure the internal parameters of the components, especially the brushes and brushholders. Both components must be properly aligned and calibrated to avoid electric arcs to the internal insulation of the motor. Although there is an increasing effort to improve inspection tasks, most inspection procedures are manual, leading to unnecessary costs in inspection time, errors in data entry, and, in extreme cases, measurement errors. This research presents the design, development, and assessment of an integrated measurement prototype for measuring spring tension and other key parameters in brushholders used in electric motors. It aims to provide the mining industry with a new, fully automatic inspection system that will facilitate maintenance and checking. Our development research was carried out specifically on the brush system of a SAG grinding mill motor. These machines commonly use SIEMENS motors; however, the instrument can be easily adapted to any motor by simply changing the physical dimensions of the prototype.

Carrasco, M., Toledo, P., & Tischler, N. D. (2019). Macromolecule Particle Picking and Segmentation of a KLH Database by Unsupervised CryoEM Image Processing. Biomolecules, 9(12), 14 pp.
Abstract: Segmentation is one of the most important stages in the 3D reconstruction of macromolecule structures in cryoelectron microscopy. Due to the variability of macromolecules and the low signaltonoise ratio of the structures present, there is no generally satisfactory solution to this process. This work proposes a new unsupervised particle picking and segmentation algorithm based on the composition of two wellknown image filters: Anisotropic (PeronaMalik) diffusion and nonnegative matrix factorization. This study focused on keyhole limpet hemocyanin (KLH) macromolecules which offer both a top view and a side view. Our proposal was able to detect both types of views and separate them automatically. In our experiments, we used 30 images from the KLH dataset of 680 positive classified regions. The true positive rate was 95.1% for top views and 77.8% for side views. The false negative rate was 14.3%. Although the false positive rate was high at 21.8%, it can be lowered with a supervised classification technique.

Carrera, P., Campo, R., Mendez, R., Di Bella, G., Campos, J. L., MosqueraCorral, A., et al. (2019). Does the feeding strategy enhance the aerobic granular sludge stability treating saline effluents? Chemosphere, 226, 865–873.
Abstract: The development and stability of aerobic granular sludge (AGS) was studied in two Sequencing Batch Reactors (SBRs) treating fish canning wastewater. R1 cycle comprised a fully aerobic reaction phase, while R2 cycle included a plugflow anaerobic feeding/reaction followed by an aerobic reaction phase. The performance of the AGS reactors was compared treating the same effluents with variable salt concentrations (4.9713.45 g NaCl/L) and organic loading rates (OLR, 1.806.65 kg CODs/(m(3).d)). Granulation process was faster in R2 (day 34) than in R1 (day 90), however the granular biomass formed in the fully aerobic configuration was more stable to the variable feeding composition. Thus, in R1 solid retention times (SRT), up to 15.2 days, longer than in R2, up to 5.8 days, were achieved. These long SRT5 values helped the retention of nitrifying organisms and provoked the increase of the nitrogen removal efficiency to 80% in R1 while it was approximately of 40% in R2. However, the presence of an anaerobic feeding/reaction phase increased the organic matter removal efficiency in R2 (8090%) which was higher than in R1 with a fully aerobic phase (7585%). Furthermore, in R2 glycogenaccumulating organisms (GAOs) dominated inside the granules instead of phosphorousaccumulating organisms (PADS), suggesting that GAOs resist better the stressful conditions of a variable and highsaline influent. In terms of AGS properties an anaerobic feeding/reaction phase is not beneficial, however it enables the production of a better quality effluent. (C) 2019 Elsevier Ltd. All rights reserved.

Carrera, P., MosqueraCorral, A., Mendez, R., Campos, J. L., & del Rio, A. V. (2019). Pulsed aeration enhances aerobic granular biomass properties. Biochem. Eng. J., 149, 7 pp.
Abstract: The reduced footprint of Aerobic Granular Sludge (AGS) systems constitutes a good alternative to conventional treatments, despite their associated drawbacks (long startup periods and high aeration requirements for granules formation and integrity). This study presents a pulsed aeration regime as a strategy to overcome these problems. Two AGS sequencing batch reactors (SBRs) were operated treating lowstrength wastewater (190 mg COD/L) with pulses of 1 s ON/2 s OFF (R1) and continuous aeration (R2). Initially, different superficial gas velocities (SGV) of 3.6 cm/s (R1) and 1.2 cm/s (R2) were imposed for the same airflow (448 L/cycle). The granulation process was completed in 38 days for R1 whereas it took 48 days for R2. Denser and smaller granules were formed with pulsed regime and phosphate accumulating organisms were developed faster. The removal efficiencies were practically the same in both SBRs, being of 85% for COD, 95% for phosphorus and 30% for nitrogen. After granules formation the airflow in both reactors was reduced. For a SGV of 1.2 cm/s both systems behaved similarly. The minimum SGV required to maintain a uniform mixture of the biomass inside the reactor was 1.2 (R1) and 0.5 cm/s (R2), meaning less air consumption in the pulsed system (149 L/cycle) compared to the continuous one (179 L/min). Therefore, pulsed aeration successfully reduced granulation periods and aeration requirements in AGS systems.

Castaneda, P., & Reus, L. (2019). Suboptimal investment behavior and welfare costs: A simulation based approach. Financ. Res. Lett., 30, 170–180.
Abstract: We propose a representation of suboptimal investment behavior based on the stochastic discount factor (SDF) paradigm. Suboptimal investment behavior is rationalized as being the investor's optimal decision under a wrong SDF, while wealth trajectories and budget constraints are based on the true SDF. We develop a novel Monte Carlo simulation approach to compute the welfare costs for this suboptimal behavior. We study the suboptimal portfolio choice under CRRA preferences using two financial market models. The Monte Carlo simulation delivers comparable welfare losses to those computed in the original studies, which are based on partial differential equations (PDE) and – finitedifference schemes.

ColiniBaldeschi, R., Cominetti, R., & Scarsini, M. (2019). Price of Anarchy for Highly Congested Routing Games in Parallel Networks. Theor. Comput. Syst., 63(1), 90–113.
Abstract: We consider nonatomic routing games with one source and one destination connected by multiple parallel edges. We examine the asymptotic behavior of the price of anarchy as the inflow increases. In accordance with some empirical observations, we prove that under suitable conditions on the costs the price of anarchy is asymptotic to one. We show with some counterexamples that this is not always the case, and that these counterexamples already occur in simple networks with only 2 parallel links.

Cominetti, R., Roshchina, V., & Williamson, A. (2019). A counterexample to De Pierro's conjecture on the convergence of underrelaxed cyclic projections. Optimization, 68(1), 3–12.
Abstract: The convex feasibility problem consists in finding a point in the intersection of a finite family of closed convex sets. When the intersection is empty, a best compromise is to search for a point that minimizes the sum of the squared distances to the sets. In 2001, de Pierro conjectured that the limit cycles generated by the underrelaxed cyclic projection method converge when towards a least squares solution. While the conjecture has been confirmed under fairly general conditions, we show that it is false in general by constructing a system of three compact convex sets in for which the underrelaxed cycles do not converge.

Contreras, M., & Pena, J. P. (2019). The quantum dark side of the optimal control theory. Physica A, 515, 450–473.
Abstract: In a recent article, a generic optimal control problem was studied from a physicist's point of view (Contreras et al. 2017). Through this optic, the Pontryagin equations are equivalent to the Hamilton equations of a classical constrained system. By quantizing this constrained system, using the right ordering of the operators, the corresponding quantum dynamics given by the Schrodinger equation is equivalent to that given by the HamiltonJacobiBellman equation of Bellman's theory. The conclusion drawn there were based on certain analogies between the equations of motion of both theories. In this paper, a closer and more detailed examination of the quantization problem is carried out, by considering three possible quantization procedures: right quantization, left quantization, and Feynman's path integral approach. The Bellman theory turns out to be the classical limit h > 0 of these three different quantum theories. Also, the exact relation of the phase S(x, t) of the wave function Psi(x, t) = e(i/hS(x,t)) of the quantum theory with Bellman's cost function J(+)(x, t) is obtained. In fact, S(x, t) satisfies a 'conjugate' form of the HamiltonJacobiBellman equation, which implies that the cost functional J(+)(x, t) must necessarily satisfy the usual HamiltonJacobiBellman equation. Thus, the Bellman theory effectively corresponds to a quantum view of the optimal control problem. (C) 2018 Elsevier B.V. All rights reserved.

de Kraker, J., KujawaRoeleveld, K., Villena, M. J., & PabonPereira, C. (2019). Decentralized Valorization of Residual Flows as an Alternative to the Traditional Urban Waste Management System: The Case of Penalolen in Santiago de Chile. Sustainability, 11(22), 26 pp.
Abstract: Urban residual flows contain significant amounts of valuable nutrients, which, if recovered, could serve as input for the own city needs or those of its immediate surroundings. In this study, the possibilities for decentralized recovery of nutrient rich residual flows in Santiago, Chile, are studied by means of a case study considering technical and socioeconomic criteria. In particular, we calculate circularity indicators for organic matter (OM), nitrogen (N), and phosphorus (P) and costbenefits of household and community onsite technological alternatives. Kitchen waste (KW) and garden residues (GR) as well as urine were considered as system inputs whereas urban agriculture, municipality green, or periurban agriculture were the considered destinations for nutrients recovered. The technologies studied were anaerobic digestion, vermicomposting, and composting, while urine storage and struvite precipitation were considered for nutrient recovery from urine. Material flow analysis was used to visualize the inputs and outputs of the baseline situation (the traditional urban waste management system), and of the different household and municipality resource recovery scenarios (the decentralized valorization systems). Our findings show that decentralized valorization of KW and GR are a clear winwin policy, since they can not only produce important environmental benefits for the city in the long run, but also important cost savings considering the landfill fees and residues transportation of the current centralized waste management system.

del Rio, A. V., Campos, J. L., Da Silva, C., Pedrouso, A., & MosqueraCorral, A. (2019). Determination of the intrinsic kinetic parameters of ammoniaoxidizing and nitriteoxidizing bacteria in granular and flocculent sludge. Sep. Purif. Technol., 213, 571–577.
Abstract: The different oxygen affinities of ammoniaoxidizing (AOB) and nitriteoxidizing bacteria (NOB) are often used to define the operational strategy to achieve partial nitritation (PN) required before the anammox (AMX) process. For this purpose, apparent kinetic parameters are mainly used in the case of granular sludge, which can lead to errors when defining the operational conditions to obtain only nitritation (avoiding nitratation). In the present study, a mathematical methodology is proposed to determine the intrinsic kinetic parameters of AOB and NOB in granular sludge based on data obtained by respirometric assays. Additionally, the oxygen affinity constant (KO2) and maximum specific rate (r(max)) of flocculent and granular sludge sample, produced under mainstream and sidestream conditions were determined at various temperatures (15, 20 and 30 degrees C). The results show that for granules, the intrinsic KO2 and r(max) values were lower and higher, respectively, than the apparent values. Furthermore, the KO2 values for flocs and granules at all of the tested temperatures were lower for NOB than for AOB. The values obtained for the kinetic parameters indicated that it is impossible to maintain partial nitritation by only controlling the dissolved oxygen concentration.
Keywords: Ammonia oxidizing bacteria; Flocs; Granules; Kinetics; Monod; Nitrite oxidizing bacteria

During, G., Josserand, C., Krstulovic, G., & Rica, S. (2019). Strong turbulence for vibrating plates: Emergence of a Kolmogorov spectrum. Phys. Rev. Fluids, 4(6), 12 pp.
Abstract: In fluid turbulence, energy is transferred from one scale to another by an energy cascade that depends only on the energydissipation rate. It leads by dimensional arguments to the Kolmogorov 1941 (K41) spectrum. Here we show that the normal modes of vibrations in elastic plates also manifest an energy cascade with the same K41 spectrum in the fully nonlinear regime. In particular, we observe different patterns in the elastic deformations such as folds, developable cones, and even more complex stretching structures, in analogy with spots, swirls, vortices, and other structures in hydrodynamic turbulence. We show that the energy cascade is dominated by the kinetic contribution and that the stretching energy is at thermodynamical equilibrium. We characterize this energy cascade, the validity of the constant energydissipation rate over the scales. Finally, we discuss the role of intermittency using the correlation functions that exhibit anomalous exponents.

Elorrieta, F., Eyheramendy, S., & Palma, W. (2019). Discretetime autoregressive model for unequally spaced timeseries observations. Astron. Astrophys., 627, 11 pp.
Abstract: Most timeseries models assume that the data come from observations that are equally spaced in time. However, this assumption does not hold in many diverse scientific fields, such as astronomy, finance, and climatology, among others. There are some techniques that fit unequally spaced time series, such as the continuoustime autoregressive moving average (CARMA) processes. These models are defined as the solution of a stochastic differential equation. It is not uncommon in astronomical time series, that the time gaps between observations are large. Therefore, an alternative suitable approach to modeling astronomical time series with large gaps between observations should be based on the solution of a difference equation of a discrete process. In this work we propose a novel model to fit irregular time series called the complex irregular autoregressive (CIAR) model that is represented directly as a discretetime process. We show that the model is weakly stationary and that it can be represented as a statespace system, allowing efficient maximum likelihood estimation based on the Kalman recursions. Furthermore, we show via Monte Carlo simulations that the finite sample performance of the parameter estimation is accurate. The proposed methodology is applied to light curves from periodic variable stars, illustrating how the model can be implemented to detect poor adjustment of the harmonic model. This can occur when the period has not been accurately estimated or when the variable stars are multiperiodic. Last, we show how the CIAR model, through its state space representation, allows unobserved measurements to be forecast.
Keywords: methods: statistical; methods: data analysis; stars: general

Figueroa, A., & Atkinson, J. (2019). DualView Learning for Detecting Web Query Intents. Computer, 52(8), 34–42.
Abstract: Automatically categorizing user intent behind web queries is a key issue not only for improving information retrieval tasks but also for designing tailored displays based on the underlying intention. In this article, a multiview learning method is proposed to recognize the user intent behind web searches.

Fuenzalida, C., JerezHanckes, C., & McClarren, R. G. (2019). Uncertainty Quantification For Multigroup Diffusion Equations Using Sparse Tensor Approximations. SIAM J. Sci. Comput., 41(3), B545–B575.
Abstract: We develop a novel method to compute first and second order statistical moments of the neutron kinetic density inside a nuclear system by solving the energydependent neutron diffusion equation. Randomness comes from the lack of precise knowledge of external sources as well as of the interaction parameters, known as cross sections. Thus, the density is itself a random variable. As Monte Carlo simulations entail intense computational work, we are interested in deterministic approaches to quantify uncertainties. By assuming as given the first and second statistical moments of the excitation terms, a sparse tensor finite element approximation of the first two statistical moments of the dependent variables for each energy group can be efficiently computed in one run. Numerical experiments provided validate our derived convergence rates and point to further research avenues.

Fullenkamp, K., Montane, M., Caceres, G., & ArayaLetelier, G. (2019). Review and selection of EPCM as TES materials for building applications. Int. J. Sustain. Energy, 38(6), 561–582.
Abstract: In order to improve the thermal efficiency of building thermal energy storage (TES) systems, the feasibility of using encapsulated phase change materials (EPCMs) as heat storage media is analysed in this work. Specifically, the finite element method is used to perform thermal behaviour analyses of several EPCMs. These analyses include technical and economic assessments in order to identify the best combination of PCM and shell material, using as main parameters: thermal energy storage, heat transfer rate, materials cost, among others. The results show that EPCMs composed by Na2SO4 center dot 6H(2)O as PCM and covered by stainless steel highlight as TES materials.

Genco, F., & Genco, G. (2019). Nuclear desalination in Chile: a competitive solution. Desalin. Water Treat., 140, 24–34.
Abstract: Renewable energy sources are considered the main drive for developing at least 70% of the total energy in Chile by 2050. All major international greenhouse gases reduction agreements include growth of renewable energy sources and nuclear power as the only ways to significantly reduce emissions by the decade 204050. Chile's energy production matrix still relies heavily on fossil fuels, making very difficult to match the goal targeted by international agreements. For these reasons, the possibility of using nuclear power plants is considered. Small modular reactors (SMRs) in particular seems particularly suitable for a country like Chile for many reasons: SMRs are scalable and can provide energy in remote locations with no or limited grids (Atacama desert); SMRs can cope easily with future demands for expansion, thanks to their modularity; SMRs are cost effective and use all the latest developments in safety. This paper examines, using IAEA DEEP 5 economic software, the costs of nuclear desalinated water produced for the Chilean mining industry. Comparisons with respect to existing fossil fuels solutions show that the final cost is very competitive and allow for significant reduction of CO2 emissions.

Girard, A., Roberts, C., Simon, F., & Ordonez, J. (2019). Solar electricity production and taxi electrical vehicle conversion in Chile. J. Clean Prod., 210, 1261–1269.
Abstract: Carbon emissions from the Chilean public transport sector have doubled between 2000 and 2013. Thus, the need to find alternative cleanair solutions is becoming increasingly critical. With this in mind, this paper addresses a solution to the aforementioned problem by studying the conversion of both taxis and “colectivos” (public taxis with defined routes) into electric vehicles (EV) to be used in the Chilean public transport sector. In Chile, 80% of taxis are Nissan V16s, meaning that all of these vehicles will be replaced and end up in landfills within the next 58 years. This study presents an option to give a second life to these vehicles, addressing environmental and financial issues. It compares emissions from the Nissan V16's conventional internal combustion engine (ICE) with an equivalent electric conversion prototype. Furthermore, it analyses the CO2 emissions from the EV that has been fully charged by the Chilean grid as well as one that has been charged by a solar photovoltaic system. A solar recharging station for EV taxis is designed, taking advantage of the high levels of solar radiation in Chile. The results show that EV conversion does not lead to real environmental benefits, in comparison to its ICE equivalent, when it is charged with the grid. However, the results also show a considerable decrease in cost and CO2 emissions per km travelled when using solar energy to charge the batteries. Future challenges include identifying solutions to cope with solar intermittence and minimizing CO2 emissions during periods of low radiation. (C) 2018 Elsevier Ltd. All rights reserved.
Keywords: Electric vehicle; Public transport; CO2 emissions; Solar charging station; Chile

Godio, A., & Seccatore, J. (2019). Measuring the Reduction of the Confinement along the Evolution of a Burn Cut. Appl. Sci.Basel, 9(23), 17 pp.
Abstract: We provide an analysis of a tunnel opening cut in a tunnel face. In particular, we focus on the effect of a “burn cut,” which is a typical parallel hole cut. As the evolution of the opening consists of an increase in the volume of the cut prism and the consequent reduction of confinement of the holes along the initiation sequence, we analyze such an evolution using photographic documentation, as well as evaluating the reduction of confinement by measuring the energy transferred from the explosive charge to the rock mass. The energy was estimated by monitoring and analyzing the vibrations induced by the blasting at three different points. We adopted lowcost shock sensors for monitoring the effect of the detonation times at short distance from the blast (about 10 m). The results show an evident reduction of the shock transfer to the rock mass (i.e., a reduction of confinement) with the increase of the cavity opening. Nevertheless, when only the response of the piezometric sensors was considered, a disparity in behavior among the sensors was noted. On the other hand, when the sensor response was integrated over time, the behavior of all sensors normalized, showing the need to focus both on the oscillation and the duration to properly address the shock effect.
Keywords: blasting; vibrations; burn cut

Hamant, O., Inoue, D., Bouchez, D., Dumais, J., & Mjolsness, E. (2019). Are microtubules tension sensors? Nat. Commun., 10, 12 pp.
Abstract: Mechanical signals play many roles in cell and developmental biology. Several mechanotransduction pathways have been uncovered, but the mechanisms identified so far only address the perception of stress intensity. Mechanical stresses are tensorial in nature, and thus provide dual mechanical information: stress magnitude and direction. Here we propose a parsimonious mechanism for the perception of the principal stress direction. In vitro experiments show that microtubules are stabilized under tension. Based on these results, we explore the possibility that such microtubule stabilization operates in vivo, most notably in plant cells where turgordriven tensile stresses exceed greatly those observed in animal cells.

Harrison, R., & Lagunoff, R. (2019). Tipping points and businessasusual in a global commons. J. Econ. Behav. Organ., 163, 386–408.
Abstract: This paper analyzes a dynamic strategic model of resource extraction from a global commons. Countries derive benefits from both direct extraction and aggregate conservation of an open access resource. Each period, a country's output depends both on its resource usage and on the global stock of the resource stored within the ecosystem. Leading examples are ocean fisheries, habitat preservation, forestry, and land carbon biomass. The production coefficients on these inputs vary across countries and evolve stochastically over time. A Businessasusual (BAU) equilibrium characterizes each country's resource usage in the absence of an effective international agreement. Under nonconcave resource dynamics, depletion of the resource in a BAU equilibrium may reach a tipping point below which the stock spirals downward toward a steady state of marginal sustainability. Under the assumptions of the model, the tipping points emerge endogenously. If the number of extractors exceeds some fixed, finite bound, the commons always tips regardless of the initial stock. We find that countries will accelerate their rates of extraction the closer they are to reaching the lowend steady state. By contrast, in the socially efficient plan the commons never tips if the initial stock is large. (C) 2019 Elsevier B.V. All rights reserved.
