Arquitectura Computacional para la Inferencia deuna CNN Cuantizada para Detectar FibrilaciónAuricular

Atrial Fibrillation is a common cardiac arrhythmia, which is characterized by an abnormal heartbeat rhythm that can be life-threatening. Recently, researchers have proposed several Convolutional Neural Networks (CNNs) to detect Atrial Fibrillation. CNNs have high requirements on computing and memory resources, which usually demand the use of High Performance Computing (eg, GPUs). This high energy demand is a challenge for portable devices. Therefore, efficient hardware implementations are required. We propose a computational architecture for the inference of a Quantized Convolutional Neural Network (Q-CNN) that allows the detection of the Atrial Fibrillation (AF). The architecture exploits data-level parallelism by incorporating SIMD-based vector units, which is optimized in terms of computation and storage and also optimized to perform both the convolutional and fully connected layers. The computational architecture was implemented and tested in a Xilinx Artix-7 FPGA. We present the experimental results regarding the quantization process in a different number of bits, hardware resources, and precision. The results show an accuracy of 94% accuracy for 22-bits. This work aims to be the basis for the future implementation of a portable, low-cost, and high-reliability device for the diagnosis of Atrial Fibrillation.La fibrilación auricular es una arritmia cardíaca común, que se caracte-riza por un ritmo cardíaco anormal que puede poner en peligro la vida.Recientemente, se han propuesto varias Redes Neuronales Convoluciona-les (CNNs, por sus siglas en inglés) para detectar la fibrilación auricular.Las CNN tienen altos requisitos de recursos informáticos y de memoria,lo que generalmente demanda el uso Computación de Altro Rendimientocomo por ejemplo GPUs. Esta alta demanda de energía es un desafío pa-ra los dispositivos portátiles. Por lo tanto, se requieren implementacionesde hardware eficientes. Proponemos una arquitectura computacional pa-ra la inferencia de una Red Neural Convolucional Cuantizada (Q-CNN)que permite la detección de la Fibrilación Auricular (FA). La arquitecturaaprovecha el paralelismo a nivel de datos, incorporando unidades vecto-riales basadas en SIMD, que están optimizadas en términos de cálculoy almacenamiento. El diseño también se optimizó para realizar tanto lascapas convolucionales como las capas completamente conectadas. La ar-quitectura computacional se implementó y probó en una FPGA XilinxArtix-7. Presentamos los resultados experimentales con respecto al proce-so de cuantización en un número diferente de bits, recursos de hardwarey precisión. Los resultados muestran una precisión del 94 % para 22 bits.Este trabajo pretende ser la base para la futura implementación de undispositivo portátil, de bajo costo y alta confiabilidad para el diagnósticode Fibrilación Auricular

Slurry preparation methods affect dental porcelain reliability

One-step and incremental mixing procedures are currently used to produce dental ceramic pastes. In the ceramic industry, high quality is obtained using one-step mixing, but in dentistry, the best method has not been yet determined. The purpose of this study is to evaluate the effects of 2 mixing techniques on the biaxial flexural strength and microstructure of dental porcelain. Feldspathic porcelain discs (2 × 15 mm in diameter) were produced and divided according to the ceramic paste preparation method, powder-liquid incremental mixing group (n=50) or one-step mixing, as a control group (n=50). Specimens were tested for biaxial flexural strength and characterized using porosimetry, relative humidity, SEM/EDS, XRD, and FT-IR analyses. Statistical analysis was conducted using Weibull statistics. The Weibull modulus, characteristic strength and relative humidity were compared between groups, using Student's t-test and Mann-Whitney U test (a=.05). The powder-liquid incremental mixing group showed significantly higher values (SD) of Weibull modulus (6.74 (0.70), P<.001) and characteristic strength (79.87 (2.01) MPa, P<.001) when compared to the one-step mixing group (4.94 (0.94) and 75.95 (2.61) MPa). Significantly lower mean (SD) relative humidity values (P=.009) were found for powder-liquid incremental mixing group (20% (0.5%)) compared to one-step mixing group (22% (1%)). XRD spectra showed that the one-step mixing group produced higher amounts of the amorphous phase. Specimens produced by the incremental mixing technique showed higher biaxial flexural strength than one-step mixing

Oxidación de p-nitrofenol usando TiO2 -adenosina monofosfato | Oxidation of p-nitrophenol using TiO2 -adenosin monophosphate

La superficie del dióxido de titanio se modificó con los nucleótidos Adenosina 3’-monofosfato (AMP´3)y Adenosina 5’-monofosfato (AMP´5). La adsorción de los nucleótidos se ajustó al modelo de adsorción deLangmuir, determinando que la condición más apropiada para modificar el TiO2 fue a pH neutro. Los espectrosUV-Visibles por Reflectancia Difusa e Infrarrojo por Reflectancia Total Atenuada demostraron que ocurrió laquimisorción de los nucleótidos sobre el TiO2 (anatasa). Los nuevos catalizadores (TiO2-nucleótidos) aumentaronla fotodegradación del p-nitrofenol en un amplio intervalo de pH al compararlo con el dióxido de titanio precursor.La mayor fotoactividad se generó al utilizar los nuevos fotocatalizadores en la degradación del p-nitrofenol apH = 6, obteniendo altos valores para las constantes de reacción de pseudo primer orden (0,0254 min-1 y 0,0244min-1 para el TiO2-AMP´3 y TiO2-AMP´5, respectivamente). Para todos los pH se presentó la siguiente tendenciade fotodegradación: TiO2-AMP´3 @ TiO2-AMP´5 > TiO2. Al aplicar el modelo de Langmuir-Hinshelwood sedeterminó que la contribución del factor cinético asociado a la reacción superficial gobierna la fotodegradacióndel contaminante.Palabras clave: TiO2 anatasa, fotodegradación, p-nitrofenol, nucleótido.ABSTRACTThe surface of TiO2 was modified with the nucleotides adenosine 3’-monophosphate (AMP’3) and Adenosine5’-monophosphate (AMP’5). The adsorption of nucleotides was adjusted to Langmuir´s adsorption model,determining that the optimal condition for TiO2 modification was at neutral pH. UV-Visible Diffuse Reflectanceand IR Attenuated Total Reflectance spectra show that the chemisorption of nucleotides take placed on TiO2anatase. The new catalysts (TiO2-nucleotide) improved the photodegradation of p-nitrophenol in a wide rangeof pH as compared with the titanium dioxide precursor. Most photoactivity was generated by using the newphotocatalytic in the degradation of p-nitrophenol at pH = 6, obtaining high values for the pseudo first orderkinetic constant (0.0254 min-1 and 0.0244 min-1 for TiO2-AMP’3 and TiO2-AMP’5, respectively). For all pH,the trend obtained for the photodegradation was: TiO2-AMP´3 @ TiO2-AMP’5 > TiO2. Langmuir-Hinshelwoodkinetics shows that the contribution of the surface reaction rate governs the oxidation of the contaminant.Key words: TiO2 anatase, photodegradation, p-nitrophenol, nucleotide

MPC for optimal dispatch of an AC-linked hybrid PV/wind/biomass/H2 system incorporating demand response

[EN] A Model Predictive Control (MPC) strategy based on the Evolutionary Algorithms (EA) is proposed for the optimal dispatch of renewable generation units and demand response in a grid-tied hybrid system. The generating system is based on the experimental setup installed in a Distributed Energy Resources Laboratory (LabDER), which includes an AC micro-grid with small scale PV/Wind/Biomass systems. Energy storage is by lead-acid batteries and an H2 system (electrolyzer, H2 cylinders and Fuel Cell). The energy demand is residential in nature, consisting of a base load plus others that can be disconnected or moved to other times of the day within a demand response program. Based on the experimental data from each of the LabDER renewable generation and storage systems, a micro-grid operating model was developed in MATLAB(C) to simulate energy flows and their interaction with the grid. The proposed optimization algorithm seeks the minimum hourly cost of the energy consumed by the demand and the maximum use of renewable resources, using the minimum computational resources. The simulation results of the experimental micro-grid are given with seasonal data and the benefits of using the algorithm are pointed out.Acevedo-Arenas, CY.; Correcher Salvador, A.; Sánchez-Diaz, C.; Ariza-Chacón, HE.; Alfonso-Solar, D.; Vargas-Salgado, C.; Petit-Suarez, JF. (2019). MPC for optimal dispatch of an AC-linked hybrid PV/wind/biomass/H2 system incorporating demand response. Energy Conversion and Management. 186:241-257. https://doi.org/10.1016/j.enconman.2019.02.044S24125718

Sistemas de Comunicacion Inalambrica MIMO - OFDM

En este articulo tutorial, se presenta la fundamentacion basica de la tecnica demodulation multiportadora OFDM (&gt;Orthogonal Frequency Division Multiplexing). Y serealiza una introduction a los sistemas de transmision MIMO (Multi-Input and MultiOutput). Adicionalmente, se muestra un resumen de las estructuras espaciales de estossistemas. Finalmente se realiza una revision, de la estructura obtenida al combinar laestructura MIMO y la tecnica de modulation OFDM

Revalorización de residuos de equipos eléctricos y electrónicos en Colombia: una alternativa para la obtención de metales preciosos y metales para la industria

This article aims to review the global context, and especially the Colombian context, regarding the management of waste electrical and electronic appliances, their use, recovery and the main extraction methods for high added-value base and precious metals. A literature review was carried out to obtain the quantities of residues, their main components and the extraction methods for base and precious metals; for Colombia, a case study was carried out in which, through a hydrometallurgy process applied to cellular phones, the quantities of base and precious metals that can be obtained were calculated. Only 15.5 % of e-waste in the world is recycled, the main recyclable components are iron (Fe), copper (Cu), aluminum (Al), lead (Pb), nickel (Ni), silver (Ag), gold (Au) and palladium (Pd), and that using e-waste as a source of metals could reduce energy consumption by 60-95 %. For the case study in Colombia, it was found that 3.8 t/year of Cu, 3.5 t/year of Fe, 56.5 kg/year of Ag, 6 kg/year of Pd and 10 kg/year of Au could be obtained. The conclusion is that recovering metals from electrical and electronic waste is feasible and that alternatives should be sought to take advantage of them due to their potential added value.El objetivo de este artículo es revisar el contexto mundial, y especialmente el colombiano, respecto al manejo de los residuos de equipos eléctricos y electrónicos, su aprovechamiento, recuperación y los principales métodos para la extracción de metales base y preciosos de alto valor agregado. Para ello, se realizó una revisión bibliográfica para obtener las cantidades de residuos, sus componentes principales y los métodos de extracción de metales base y preciosos; para Colombia, se realizó un estudio de caso, en el que, mediante un proceso de hidrometalurgia aplicado a teléfonos celulares, se calcularon las cantidades de metales base y preciosos que se pueden obtener. Se encontró que solo se aprovecha el 15,5 % de los residuos electrónicos en el mundo, que los principales componentes reciclables son el hierro (Fe), el cobre (Cu), el aluminio (Al), el plomo (Pb), el níquel (Ni), la plata (Ag), el oro (Au) y el paladio (Pd), y que el uso de los residuos electrónicos como fuente de metales podría reducir el consumo de energía entre 60 % y 95 %. Para el estudio de caso en Colombia, se encontró que se podrían obtener 3,8 t/año de Cu, 3,5 t/año de Fe, 56,5 kg/año de Ag, 6 kg/año de Pd y 10 kg/año de Au. Se concluye que es viable la recuperación de metales a partir de residuos eléctricos y electrónicos y que se deben buscar alternativas para aprovecharlos debido a su potencial valor agregado

Quantum states and specific heat of low-density He gas adsorbed within the carbon nanotube interstitial channels: Band structure effects and potential dependence

We calculate the energy-band structure of a He atom trapped within the interstitial channel between close-packed nanotubes within a bundle and its influence on the specific heat of the adsorbed gas. A robust prediction of our calculations is that the contribution of the low-density adsorbed gas to the specific heat of the nanotube material shows pronounced nonmonotonic variations with temperature. These variations are shown to be closely related to the band gaps in the adsorbate density of states