Chaotic image encryption using hopfield and hindmarsh–rose neurons implemented on FPGA

Chaotic systems implemented by artificial neural networks are good candidates for data encryption. In this manner, this paper introduces the cryptographic application of the Hopfield and the Hindmarsh–Rose neurons. The contribution is focused on finding suitable coefficient values of the neurons to generate robust random binary sequences that can be used in image encryption. This task is performed by evaluating the bifurcation diagrams from which one chooses appropriate coefficient values of the mathematical models that produce high positive Lyapunov exponent and Kaplan–Yorke dimension values, which are computed using TISEAN. The randomness of both the Hopfield and the Hindmarsh–Rose neurons is evaluated from chaotic time series data by performing National Institute of Standard and Technology (NIST) tests. The implementation of both neurons is done using field-programmable gate arrays whose architectures are used to develop an encryption system for RGB images. The success of the encryption system is confirmed by performing correlation, histogram, variance, entropy, and Number of Pixel Change Rate (NPCR) tests

Sistema Integrado de Monitoreo Ambiental de Caldas – SIMAC Sistema de Vigilancia de Calidad del Aire en Manizales

La dinámica actual de la población tiene mayor necesidad de consumo debido a su acelerado crecimiento. Esta dinámica trae consigo una mayor producción industrial, altos índices de motorización y por ende mayores niveles de emisión de contaminantes, entre los cuales se destacan el monóxido de carbono (CO), óxidos de nitrógeno (NOx), dióxido de azufre (SO2), ozono troposférico (O3) y material particulado (PM). Lo anterior genera impactos negativos en la calidad del aire de los centros urbanos y en los ecosistemas circundantes. En la dinámica del Sistema de Vigilancia de la Calidad del Aire (SVCA) intervienen diferentes elementos que requieren una clasificación para lograr un mayor entendimiento del mismo. En este sentido, las emisiones son ocasionadas principalmente por fuentes antropogénicas como el parque automotor y la producción industrial, o por fuentes naturales, como en el caso de la ciudad de Manizales, las emisiones generadas por el volcán Nevado del Ruiz. Estas emisiones van a la atmósfera donde se ven afectadas por las condiciones climáticas que favorecen o no las reacciones químicas, deposición, dispersión y transporte de los contaminantes. El objetivo de las estaciones de monitoreo instaladas en la ciudad es cuantificar los diferentes contaminantes presentes en el aire ambiente. Posteriormente, estos datos son procesados y publicados periódicamente, generando información de gran utilidad para la toma de decisiones que permitan alcanzar un desarrollo sostenible para la ciudad y una adecuada gestión de la calidad del air

Collective outflow from a small multiple stellar system

The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with $M$ > 15 $M$$\bigodot$ , may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H$_2$ and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of two to three. © 2014. The American Astronomical Society. All rights reserved.

Colloidal processing of fully stabilized zirconia laminates comprising graphene oxide-enriched layers

Multilayer materials have demonstrated to provide an efficient mechanism for toughening by deflection of a propagating crack by weak interlayers. Therefore, the aim of this work is to study the colloidal processing of 8 mol% yttria stabilized zirconia (8YSZ) based laminates by intercalating thin layers of graphene enriched with 8YSZ, and to evaluate the advantages of such multilayered structure in the propagation of cracks induced by indentation. Green tapes of 8YSZ and graphene-oxide with YSZ were obtained by aqueous tape casting and sintered in one-step by spark plasma sintering at 1400 degrees C. Microindentation results showed that the indentation cracks propagate within the horizontal direction within the ceramic layer, but in the cross-sectional direction the presence of the GO-rich layers stops the cracks without deflection or bifurcation. The hardness and elastic modulus values were higher than 17.6 GPa and 230 GPa, respectively, and similar for all layers.This work has been supported by the Spanish Ministry of Economy and Competitiveness (project MAT2015-67586-C3-R) and the Generalitat Valenciana by the financial support for the GV/2014/009 project. M.D. Salvador thanks to CAPES-Programa Ciencias sem Fronteiras (Brazil) for the concession of a PVE project No. A086/2013. A. Borrell, acknowledges the Spanish Ministry of Economy and Competitiveness for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839).Rincón, A.; Moreno, R.; Gutierrez González, FC.; Sainz, R.; Salvador Moya, MD.; Borrell Tomás, MA. (2016). Colloidal processing of fully stabilized zirconia laminates comprising graphene oxide-enriched layers. Journal of the European Ceramic Society. 36(7):1797-1804. https://doi.org/10.1016/j.jeurceramsoc.2016.01.035S1797180436

Linear Relationship between Resilience, Learning Approaches, and Coping Strategies to Predict Achievement in Undergraduate Students

This research has been developed within the framework of the R & D Projects EDU2011-24805 (2011-2015) (MICIN, Spain). See:- http://www.estres.investigacion-psicopedagogica.org/englishThe aim of the present research was to analyze the linear relationship between resilience (meta-motivational variable), learning approaches (meta-cognitive variables), strategies for coping with academic stress (meta-emotional variable) and academic achievement, necessary in the context of university academic stress. A total of 656 students from a southern university in Spain completed different questionnaires: a resiliency scale, a coping strategies scale, and a study process questionnaire. Correlations and structural modeling were used for data analyses. There was a positive and significant linear association showing a relationship of association and prediction of resilience to the deep learning approach, and problem-centered coping strategies. In a complementary way, these variables positively and significantly predicted the academic achievement of university students. These results enabled a linear relationship of association and consistent and differential prediction to be established among the variables studied. Implications for future research are set out

Local and global environmental effects on galaxies and active galactic nuclei

We study the properties of SDSS galaxies with and without AGN detection as a function of the local and global environment measured via the local density, the mass of the galaxy host group (parameterised by the group luminosity) and distance to massive clusters. Our results can be divided in two main subjects, the environments of galaxies and their relation to the assembly of their host haloes, and the environments of AGN. (i) For the full SDSS sample, we find indications that the local galaxy density is the most efficient parameter to separate galaxy populations, but we also find that galaxies at fixed local density show some remaining variation of their properties as a function of the distance to the nearest cluster of galaxies (in a range of 0 to 10 cluster virial radii). These differences seem to become less significant if the galaxy samples are additionally constrained to be hosted by groups of similar total luminosity. (ii) In AGN host galaxies, the morphology-density relation is much less noticeable when compared to the behaviour of the full SDSS sample. In order to interpret this result we analyse control samples constructed using galaxies with no detected AGN activity with matching distributions of redshifts, stellar masses, r-band luminosities, g-r colours, concentrations, local densities, host group luminosities, and fractions of central and satellite galaxies. The control samples also show a similar small dependence on the local density indicating an influence from the AGN selection, but their colours are slightly bluer compared to the AGN hosts regardless of local density. Furthermore, even when the local density is held fixed at intermediate or high values, and the distance to the closest cluster of galaxies is allowed to vary, AGN control galaxies away from clusters tend to be bluer than the AGN hosts. (ABRIDGED)Comment: 18 pages, 7 figures, MNRAS, in pres