7,453 research outputs found

    Quality in Testing Laboratories: A Real Case in a Spanish Fuel Laboratory

    Get PDF
    Quality management is the chosen option by those organizations that maintain a strong commitment to excellence in their products, services, and processes. The technical competence of a testing laboratory is essential to provide confidence in the results issued to its clients: administrations, companies, or individuals who request their services. The implementation of a quality system, with international recognition, facilitates and enables laboratory projection in national and international forums. The study shows the steps followed by a fuel laboratory (R + D + i), integrated in a Spanish university, to implement the quality standards established in ISO/IEC 17025 and ISO 9001. Despite its small size, the laboratory maintains high-quality standards. Obtaining ISO/IEC 17025 accreditation has allowed the laboratory to recognize its technical competence at a national and international level, greater visibility, and better positioning among laboratories that offer the same services, which has increased the number of customers and has achieved their loyalty

    Distillation: Basic Test in Quality Control of Automotive Fuels

    Get PDF
    The petroleum-derived automotive fuels available on the market today have different characteristics from those that were available a decade ago, mainly due to the promotion of the use of biofuels. However, the study of their distillation curves remains a basic test for their quality control. The ISO 3405 Standard has been the basis of the test procedure for the determination of the distillation characteristics of petroleum-derived automotive fuels at atmospheric pressure. This test is essential for the quality control of this type of products because of the extensive information that can be extracted from the interpretation of its results. The introduction of biofuels (bioethanol, biodiesel) in the new automotive fuel formulations, petrol and diesel fuels, made imperative to review ISO 3405:2000 in 2011. This paper studies the most significant changes between the two versions of the ISO 3405. The latest edition of the Standard is broader in scope; it has been modified in order to include the new fuel formulations which result from biofuel mixtures and the new criteria for repeatability and reproducibility calculation. This paper studies the most significant changes between the two versions of the ISO 3405 Standard together with a field study of commercial automotive fuel samples selection (with and without biofuel blend) and certified reference materials

    Spatial and temporal variability of CO2 emisions in soils under conventional tillage and no-till farming

    Get PDF
    Agricultural soils can act as a carbon sink depending on the soil management practices employed. As a result of this functional duality, soil management systems are present in international documents relating to climate change mitigation. Agricultural practices are responsible for 14% of total greenhouse gas emissions (GHG’s) (MMA, 2009)(1). Conservation agriculture (CA) is one of the most effective agricultural systems for reducing CO2 emissions, as it increases the sequestration of atmospheric carbon in the soil. In order to assess the performance of CA in terms of CO2 emissions, a field trial was conducted comparing soil derived CO2 fluxes under No-till (NT) farming and under conventional tillage. Three pilot farms were selected in the cereal-growing area of southern Spain, located in Las Cabezas de San Juan (Seville), Carmona (Seville) and Cordoba. Each pilot farm comprises six experimental plots with an approximate area of five hectares; three of the six plots implement CA practices, while the other three use conventional tillage techniques. The subdivision of each tillage system into 3 plots allowed the simultaneous cropping of the three crops of the wheat-sunflower-legume rotation each year. Results showed that carbon dioxide emissions were 31 to 91% higher in tilled soils than in untilled soils, and that there was a great seasonal variability of CO2 emissions, as weather conditions also differed considerably for the different sampling periods. In all cases, the CO2 fluxes emitted into the atmosphere were always higher when soil was subject to conventional tillage

    Características de la anidación de la tortuga verde Chelonia mydas (Testudinata, Cheloniidae) en la playa Caleta de los Piojos, Cuba, a partir de marcaciones externas

    Get PDF
    Green turtle (Chelonia mydas) females nesting during 2002 and 2003 nesting seasons at Caleta de los Piojos Beach, Cuba, were studied using data from individual tagging. Nesting occurred on average twice per season with a mean interval of 10.9 days. A high number of turtles nested only once per season (39% and 40% respectively). The percentage of failed multiple nesting attempts was high in both seasons. However, the percentage of failed attempts prior to the first nesting was higher in the 2003 season. Vegetation areas seem to be the most suitable sites for nesting and have a significant effect on nest–site selection behaviour. Fidelity to first nest–site was high, 50.3% and 72.9% respectively for 2002 and 2003. Observed mean clutch size (117 eggs) was closely related to body dimensions. Key words: Green turtle, Chelonia mydas, Nesting, Tagging, Guanahacabibes Peninsula.En el presente estudio se caracterizan aspectos reproductivos de las hembras de tortuga verde (Chelonia mydas), que anidaron entre los años 2002 y 2003, en la playa Caleta de los Piojos, Cuba. Se utiliza la información recopilada a partir de la colocación de marcas metálicas en cada tortuga observada. Durante las temporadas en estudio se comprobó que las tortugas anidan dos veces como promedio, con intervalo de 10.9 días. Un gran número de tortugas anidaron sólo una vez en toda la etapa reproductiva (39% y 40% respectivamente). El mayor porcentaje de intentos fallidos de anidación para ambos años ocurrió entre anidaciones consecutivas. Sin embargo en la temporada de anidación 2003 se observó un mayor porcentaje de intentos fallidos antes de la primera anidación, respecto al año 2002. La zona de vegetación fue la más utilizada para la anidación y tiene un efecto significativo en la conducta de selección del sitio de anidación. Se observó un 50,3% y 72,9% respectivamente para 2002 y 2003, de fidelidad al lugar de primera anidación. El tamaño promedio de la nidada (117 huevos) depende de las dimensiones corporales de la hembra anidadora. Palabras clave: Tortuga verde, Chelonia mydas, Anidación, Marcación, Península de Guanahacabibes

    Performance evaluation and limitations of a vision system on a reconfigurable/programmable chip

    Get PDF
    This paper presents a survey of the characteristics of a vision system implemented in a reconfigurable/programmable chip (FPGA). System limitations and performance have been evaluated in order to derive specifications and constraints for further vision system synthesis. The system hereby reported has a conventional architecture. It consists in a central microprocessor (CPU) and the necessary peripheral elements for data acquisition, data storage and communications. It has been designed to stand alone, but a link to the programming and debugging tools running in a digital host (PC) is provided. In order to alleviate the computational load of the central microprocessor, we have designed a visual co-processor in charge of the low-level image processing tasks. It operates autonomously, commanded by the CPU, as another system peripheral. The complete system, without the sensor, has been implemented in a single reconfigurable chip as a SOPC. The incorporation of a dedicated visual co-processor, with specific circuitry for low-level image processing acceleration, enhances the system throughput outperforming conventional processing schemes. However, time-multiplexing of the dedicated hardware remains a limiting factor for the achievable peak computing power. We have quantified this effect and sketched possible solutions, like replication of the specific image processing hardware. © J.UCS.This work has been partially funded by project FIT-330100-2005-162 of the Spanish Ministry of Industry, Tourism and Commerce. The work of F. J. Sánchez-Fernández is supported by a grant of the Spanish Ministry of Education and Science.Peer Reviewe

    The cosmic evolution of the spatially-resolved star formation rate and stellar mass of the CALIFA survey

    Get PDF
    We investigate the cosmic evolution of the absolute and specific star formation rate (SFR, sSFR) of galaxies as derived from a spatially-resolved study of the stellar populations in a set of 366 nearby galaxies from the CALIFA survey. The analysis combines GALEX and SDSS images with the 4000 break, H_beta, and [MgFe] indices measured from the datacubes, to constrain parametric models for the SFH, which are then used to study the cosmic evolution of the star formation rate density (SFRD), the sSFR, the main sequence of star formation (MSSF), and the stellar mass density (SMD). A delayed-tau model, provides the best results, in good agreement with those obtained from cosmological surveys. Our main results from this model are: a) The time since the onset of the star formation is larger in the inner regions than in the outer ones, while tau is similar or smaller in the inner than in the outer regions. b) The sSFR declines rapidly as the Universe evolves, and faster for early than for late type galaxies, and for the inner than for the outer regions of galaxies. c) SFRD and SMD agree well with results from cosmological surveys. At z< 0.5, most star formation takes place in the outer regions of late spiral galaxies, while at z>2 the inner regions of the progenitors of the current E and S0 are the major contributors to SFRD. d) The inner regions of galaxies are the major contributor to SMD at z> 0.5, growing their mass faster than the outer regions, with a lookback time at 50% SMD of 9 and 6 Gyr for the inner and outer regions. e) The MSSF follows a power-law at high redshift, with the slope evolving with time, but always being sub-linear. f) In agreement with galaxy surveys at different redshifts, the average SFH of CALIFA galaxies indicates that galaxies grow their mass mainly in a mode that is well represented by a delayed-tau model, with the peak at z~2 and an e-folding time of 3.9 Gyr.Comment: 23 pages, 16 figures, 6 tables, accepted for publication in Astronomy & Astrophysics. *Abridged abstract

    Waste-based materials in residential house construction

    Get PDF
    Waste from the construction sector has been increasing considerably in recent years, making it urgent to find alternatives to this waste that will enable us to preserve the environment and ecosystems. Many studies demonstrate the viability of using this and other waste in the construction sector, such as wood, ashes, and plastics. This article presents a review of research works where residual materials have been applied in the construction sector. To achieve this objective, a total of 35 articles were reviewed, published in English-speaking journals between 2015 and 2023. This review shows that, although in recent years efforts have been made for the application of waste materials in the construction sector has been significant, however, there is still work to be done in the study of the behavior of these residual materials, such as the emission of greenhouse gases, as well as the importance of residual materials pretreatment to ensure compatibility with the rest of the components. Another important aspect is that most studies consider environmental aspects without taking into account social and economic issues surrounding them in the construction sector

    The alternative of EXERGAMEs in improving the quality of life of the elderly

    Get PDF
    Actualmente vivimos en una sociedad claramente condicionada por el alcance de las nuevas tecnologías. Asimismo, el significativo aumento del número de nuestros mayores constituye otra característica que la determina. Esta situación plantea la necesidad de propuestas que promuevan la calidad de vida y bienestar en la tercera edad. Para ello, se ha realizado una revisión bibliográfica considerando el ámbito de la actividad física, el cual se concretada como una de las bazas más importantes a tratar para lograr ese objetivo; y el papel que pueden jugar las nuevas tecnologías en él, concretamente los «Exergames». Por ello, y con el fin de buscar alternativas para la mejora de la salud en la tercera edad, este estudio pretende poner en relieve la utilización de las nuevas tecnologías con dicha meta. En este sentido, se destaca el uso de los videojuegos activos, una tecnología que lleva en auge desde hace algún tiempo, con la cual nuestros mayores podrán no solo mejorar su condición física y mental, sino su calidad de vida de forma global
    corecore