Determining the operational window of green antiscalants: A case study for calcium sulfate

The detrimental effects of inorganic scaling in industrial and domestic applications are often mitigated with scale inhibitors. Increasing environmental awareness and stringent regulations require developing more sustainable antiscalants. Testing of suitable candidates is often the rate-limiting step in development cycles, therefore we developed a high-throughput methodology to rapidly evaluate the antiscaling potential of new additives under different application conditions. Using this method we determined the performance of two potential green additives – a chelating agent and a threshold inhibitor – in delaying CaSO4 precipitation over a wide range of supersaturations, temperatures and salinities. The threshold inhibitor strongly delayed CaSO4 scaling, but its performance is highly dependent on the physicochemical conditions, with the appropriate application window comprising low salinities and mild temperatures. In contrast, the chelating agent showed a lower inhibiting capacity, but its performance remained relatively constant throughout the entire matrix of physicochemical conditions. Noteworthy, we also observed that at intermediate salinities the absolute induction time for CaSO4 precipitation is dramatically prolonged, offering a sustainable strategy to mitigate scaling. Overall, our method allows simultaneously benchmarking the scaling kinetics and testing the scale-inhibiting performance of additives, providing a direct route to a more rational design of antiscaling technologies.BI-OTIC campus de excelencia (UGR) 30.BA.94.080

Automotive Control Catalyzer to Synthetize CaCO3 from Residual Co2 Embedded Control System

La contaminación generada por el sector automotriz es un problema de medio ambiente por el que sectores gubernamentales y privados han tomado acciones para contrarrestarla. Uno de esos esfuerzos procura de proveer una solución para la emisión de gases de producidos de diferentes sistemas de combustión. El objetivo del presente proyecto es diseñar un sistema de alta calidad y confiable, capaz de transformar una cantidad considerable de los gases emitidos en nuevo combustible antes de ser liberados de vuelta al entorno. El módulo de control fue desarrollado considerando los requerimientos demandados por la industria automotriz. El controlador fue basado sobre la arquitectura AUTOSAR, este también incluyó el protocolo de comunicación estándar CAN 2.0 desempeñado con el microcontrolador validado como grado 2 por el Consejo de Electrónica Automotriz, y el sensor SHT11 usado fue certificado contra RoHS. La arquitectura de software cumple con la complejidad inherente de las especificaciones de AUTOSAR, por consiguiente, diferentes técnicas fueron requeridas para su solución, incluyendo la definición, diagramas de límites, especificación de requerimientos, interfaces de software e interacción de módulos. Una vez que los requerimientos fueron conocidos, el código fue implementado. Como resultado, este módulo puede ser categorizado como un producto de grado automotriz que puede ser introducido en el mercado automotriz.The pollution generated by the automotive sector has been an environmental issue in the latest years, and nowadays, different governmental and private sectors have taken actions on this matter. One of these efforts tries to provide a solution for contaminating gas emissions produced from different fuel combustion systems. The aim of the present project is to design a reliable and high-quality system that senses the environmental temperature, relative humidity, and calculates the dew point to control a catalyzer capable of transforming a considerable amount of exhaust gases into a new fuel component before they are released back into the environment. The control module was developed considering the requirements demanded by the automotive industry. The controller was based on an AUTOSAR architecture, it also included the standard CAN 2.0 communication protocol performed within the microcontroller validated as grade 2 by the Automotive Electronics Council, and the SHT11 sensor used was certified against RoHS. Equally important, the software architecture complied with the complexity inherent in AUTOSAR specifications. Therefore, different techniques were required for its solution, including, boundary diagram, requirement specifications, software interface, and module interaction definitions. Once these requirements where met, the code was implemented. As a result, this module could be categorized as an automotive-grade product that can be introduced in the automotive market.Consejo Nacional de Ciencia y Tecnologí

External Fluctuations in a Pattern-Forming Instability

The effect of external fluctuations on the formation of spatial patterns is analysed by means of a stochastic Swift-Hohenberg model with multiplicative space-correlated noise. Numerical simulations in two dimensions show a shift of the bifurcation point controlled by the intensity of the multiplicative noise. This shift takes place in the ordering direction (i.e. produces patterns), but its magnitude decreases with that of the noise correlation length. Analytical arguments are presented to explain these facts.Comment: 11 pages, Revtex, 10 Postscript figures added with psfig style (included). To appear in Physical Review

Selective rearrangement of Nd3+ centers in LiNbO3 under ferroelectric domain inversion by electron beam writing

The following article appeared in Physical Review B - Condensed Matter and Materials Physics 78.1 (2008): 014114 and may be found at https://journals.aps.org/prb/abstract/10.1103/PhysRevB.78.014114Different values of the electronic charge provided by a direct electron beam writing system have been used to produce polarization inverted domain regions in the micrometer range on Nd3+ optically activated LiNbO3. The effect of the electronic charge on the Nd3+ center structure has been studied by means of low-temperature luminescence from Nd3+ ions. The axial crystal field acting on the Nd3+ centers has been analyzed through the F4 3/2 energy-level splitting of the Nd3+ ions. From there we have determined the position of Nd3+ ions into the Li+ octahedra for the different unequivalent centers in domains reversed with different electronic doses. The results show that the axial crystal field acting on the unequivalent Nd3+ centers can be selectively modified by means of the different doses applied to produce the inversion of the polarization. Moreover, a control of the discrete shifts suffered by the Nd3+ ions into the Li+ octahedra after the inversion process can be carried out in the range 0-0.02Å by selecting the type of Nd center to be shifted by means of the different electronic charge. The behavior of each Nd3+ center after the polarization inversion under different doses can be discriminated and the different nature, as well as the polar character of the Nd3+ centers, is clearly manifeste

Averaged Dynamic Modeling and Control of a Quasi-Z-Source Inverter for Wind Power Applications

Typically, permanent magnet synchronous generator (PMSG)-driven wind turbines (WTs) present a two-stage power converter topology based on a DC/DC boost converter and voltage source inverter. In this study, this configuration is substituted by a quasi-Z-source inverter (qZSI), which is an attractive solution for boosting and converting the voltage from DC to AC in a single stage. A 2 MW PMSG WT with qZSI was studied herein. A switched dynamic model (SDM) of the qZSI (including the modeling of all switches and firing pulses) is not recommended for steady-state stability studies, long-term simulations, or large electric power systems. For such studies, two averaged dynamic models are proposed in this work. Both models present the same control system as the SDM, except for the generation of firing pulses, which is not necessary in the averaged models. The two proposed models were evaluated and compared with the SDM in the large-scale WT under different operating conditions, such as wind speed fluctuations, variable power references, and grid disturbances (voltage sag and 3(rd) and 5(th) order harmonics injection), in order to demonstrate their adequacy to represent the system response with a high reduction in the simulation time and computational efforts.This work was supported in part by the Spain's Ministerio de Ciencia, Innovacion y Universidades (MCIU), Agencia Estatal de Investigacion (AEI), and Fondo Europeo de Desarrollo Regional (FEDER) Union Europea (UE) under Grant RTI2018-095720-B-C32, in part by the National Council of Technological and Scientific Development (CNPq), Brazil, in part by the Federal Center for Technological Education of Minas Gerais, Brazil, under Process 23062-010087/2017-51, and in part by the Regional Ministry of Economic Transformation, Industry, Knowledge and Universities of Junta de Andalucia under Grant PY20_00317

High resolution spectroscopy of the high velocity hot post-AGB star LS III +52 24 (IRAS 22023+5249)

The first high-resolution (R~50,000) optical spectrum of the B-type star, LS III +52 24, identified as the optical counterpart of the hot post-AGB candidate IRAS 22023+5249 (I22023) is presented. We report the detailed identifications of the observed absorption and emission features in the full wavelength range (4290-9015 A) as well as the atmospheric parameters and photospheric abundances (under the Local Thermodinamic Equilibrium approximation) for the first time. The nebular parameters (Te, Ne) are also derived. We estimate Teff=24,000 K, log g=3.0, xi=7 kms-1 and the derived abundances indicate a slightly metal-deficient evolved star with C/O<1. The observed P-Cygni profiles of hydrogen and helium clearly indicate on-going post-AGB mass loss. The presence of [N II] and [S II] lines and the non-detection of [O III] indicate that photoionisation has just started. The observed spectral features, large heliocentric radial velocity, atmospheric parameters, and chemical composition indicate that I22023 is an evolved post-AGB star belonging to the old disk population. The derived nebular parameters (Te=7000 K, Ne=1.2x104 cm-3) also suggest that I22023 may be evolving into a compact, young low-excitation Planetary Nebula. Our optical spectroscopic analysis together with the recent Spitzer detection of double-dust chemistry (the simultaneous presence of carbonaceous molecules and amorphous silicates) in I22023 and other B-type post-AGB candidates may point to a binary system with a dusty disk as the stellar origin common to the hot post-AGB stars with O-rich central stars.Comment: Accepted for publication in MNRAS (22 pages, 4 figures, and 8 tables). arXiv admin note: substantial text overlap with arXiv:0707.059

Nitrogen K-shell photoabsorption

Reliable atomic data have been computed for the spectral modeling of the nitrogen K lines, which may lead to useful astrophysical diagnostics. Data sets comprise valence and K-vacancy level energies, wavelengths, Einstein $A$-coefficients, radiative and Auger widths and K-edge photoionization cross sections. An important issue is the lack of measurements which are usually employed to fine-tune calculations so as to attain spectroscopic accuracy. In order to estimate data quality, several atomic structure codes are used and extensive comparisons with previous theoretical data have been carried out. In the calculation of K photoabsorption with the Breit--Pauli $R$-matrix method, both radiation and Auger damping, which cause the smearing of the K edge, are taken into account. This work is part of a wider project to compute atomic data in the X-ray regime to be included in the database of the popular {\sc xstar} modeling code

Directional dependence of the second harmonic response in two-dimensional nonlinear photonic crystals

The following article appeared in Applied Physics Letters 96.26 (2010): 261111 and may be found at https://aip.scitation.org/doi/10.1063/1.3459975A two-dimensional periodic arrangement of alternating ferroelectric domains in LiNbO3, with asymmetric domain duty cycle has been used to demonstrate that counterpropagating beams along the polar axis can generate disparate second harmonic patterns, which are nonsymmetrical with respect to the source and the point of observation. These findings provide alternative routes to generate dissimilar light-matter interaction processes in two-dimensional structures assembled onto polar surfaces, including metals for plasmonics or biological compound

Optimal energy management system using biogeography based optimization for grid-connected MVDC microgrid with photovoltaic, hydrogen system, electric vehicles and Z-source converters

Currently, the technology associated with charging stations for electric vehicles (EV) needs to be studied and improved to further encourage its implementation. This paper presents a new energy management system (EMS) based on a Biogeography-Based Optimization (BBO) algorithm for a hybrid EV charging station with a configuration that integrates Z-source converters (ZSC) into medium voltage direct current (MVDC) grids. The EMS uses the evolutionary BBO algorithm to optimize a fitness function defining the equivalent hydrogen consumption/generation. The charging station consists of a photovoltaic (PV) system, a local grid connection, two fast charging units and two energy storage systems (ESS), a battery energy storage (BES) and a complete hydrogen system with fuel cell (FC), electrolyzer (LZ) and hydrogen tank. Through the use of the BBO algorithm, the EMS manages the energy flow among the components to keep the power balance in the system, reducing the equivalent hydrogen consumption and optimizing the equivalent hydrogen generation. The EMS and the configuration of the charging station based on ZSCs are the main contributions of the paper. The behaviour of the EMS is demonstrated with three EV connected to the charging station under different conditions of sun irradiance. In addition, the proposed EMS is compared with a simpler EMS for the optimal management of ESS in hybrid configurations. The simulation results show that the proposed EMS achieves a notable improvement in the equivalent hydrogen consumption/generation with respect to the simpler EMS. Thanks to the proposed configuration, the output voltage of the components can be upgraded to MVDC, while reducing the number of power converters compared with other configurations without ZSC.This work was partially supported by Spain's Ministerio de Ciencia, Innovaci ' on y Universidades (MCIU), Agencia Estatal de Investigaci ' on (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) Uni ' on Europea (UE) (grant number RTI2018-095720-B-C32), by the Federal Center for Technological Education of Minas Gerais, Brazil (process number 23062-010087/2017-51) and by the National Council of Technological and Scientific Development (CNPq-Brazil)