436 research outputs found

    Flexural Properties of Lumber from a 50-Year-Old Loblolly Pine Plantation

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    Flexural properties of dimension lumber from a 50-year-old loblolly pine plantation stand were evaluated. The results indicate very impressive visual grade recovery, particularly No. 1, which amounted to about 44% yield. The results also indicate that the overall degrees of compliance of visually graded lumber to standard SPIB requirements of strength and stiffness are 99 and 94%, respectively

    Flexural Properties of Lumber from Two 40-Year-Old Loblolly Pine Plantations with Different Stand Densities

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    The effects of stand density on the flexural properties and compliance-to-grade requirements of lumber from two 40-year-old loblolly pine plantations were evaluated. The results indicate that stand density is positively influencing the flexural stiffness and grade compliance of the lumber produced from these plantations. On the other hand, stand density had no effect on the flexural strength of the lumber from these plantations. The lumber from the denser 40-year-old stand, which had 28 m/50 yr site index, 2.4-by 2.4-m original spacing, never thinned, with 679 trees/ha and 11.4-sq m basal area at harvest, has 96% and 66% compliance to required flexural strength and stiffness values, respectively. The lumber from the thinned 40-year-old stand, with 28 m/50 yr site index, 2.4-by 2.4-m original spacing, thinned at age 25, with 450 trees/ha and 10.2-sq m basal area at harvest, has 96% and 53% compliance to required flexural strength and stiffness values, respectively. It is now evident from the results of these studies that even dense stands must be older than 40 years of age before they can be harvested for lumber production to ensure attainment of at least 95% lumber grade compliance, i.e., strength and stiffness values that are consistent with assigned visual grades

    Integrating Economic Performance and Process Simulation Models in Evaluating Sawmill Design Alternatives

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    This paper describes a simulation study that combines an economic performance measure and a process simulation model. This integrated approach is capable of capturing the operational and cost behavior of a sawmill system over time by taking into consideration the effects of the stochastic occurrence of machine breakdowns and other processing delays. The method is demonstrated using an actual design problem involving a profiler chipper-canter mill

    The high hydraulic conductivity of three wooded tropical peat swamps in northeast Peru : measurements and implications for hydrological function

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    This research was supported by a NERC PhD studentship to the lead author, as well as by a Dudley Stamp Memorial Award from the Royal Geographical Society.The form and functioning of peatlands depend strongly on their hydrological status, but there are few data available on the hydraulic properties of tropical peatlands. In particular, the saturated hydraulic conductivity (K) has not previously been measured in neotropical peatlands. Piezometer slug tests were used to measure K at two depths (50 and 90 cm) in three contrasting forested peatlands in the Peruvian Amazon: Quistococha, San Jorge and Buena Vista. Measured K at 50 cm depth varies between 0.00032 and 0.11 cm s−1, and at 90 cm, it varies between 0.00027 and 0.057 cm s−1. Measurements of K taken from different areas of Quistococha showed that spatial heterogeneity accounts for ~20% of the within-site variance and that depth is a good predictor of K. However, K did not vary significantly with depth at Buena Vista and San Jorge. Statistical analysis showed that ~18% of the variance in the K data can be explained by between-site differences. Simulations using a simple hydrological model suggest that the relatively high K values could lead to lowering of the water table by >10 cm within ~48 m of the peatland edge for domed peatlands, if subjected to a drought lasting 30 days. However, under current climatic conditions, even with high K, peatlands would be unable to shed the large amount of water entering the system via rainfall through subsurface flow alone. We conclude that most of the water leaves these peatlands via overland flow and/or evapotranspiration.PostprintPeer reviewe

    Coctel de bacteriófagos como sustituto de promotores de crecimiento tipo antibiótico en avicultura

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    Aviculture is forced to find alternatives to replace antibiotic-type growth promoters to reduce antimicrobial resistance. Among these alternatives we have bacteriophages that are the natural predators of bacteria; however, research point out to their use as therapeutics and not as growth promoters. For this reason, this review article focuses on discussing and projecting the use of lithic bacteriophage cocktails as growth promoters in commercial breeding of broilers, laying hens and quails. Evaluating its effects on production parameters, its application in drinking water and food, phage protection strategies on gastrointestinal pH changes and high pelleting temperatures, strategies against phage-resistance, its effects on the intestinal microbiota, and the use of autophages versus commercial products. It is concluded that the optimal use of bacteriophages in aviculture is through mixed cocktails of protected lithic autophages. Finally, it is recommended to compare the use of mixed lithic autophage cocktails with mixed commercial phage cocktails that exist on the market; Additionally, the combination of mixed cocktails of protected lithic autophages with other alternatives such as probiotics, prebiotics, essential oils and organic acids should be evaluated, and this combination should be compared with the use of growth-promoting antibiotics.La industria avícola se ve en la obligación de encontrar alternativas que sustituyan a los promotores de crecimiento de tipo antibiótico para reducir la resistencia antimicrobiana. Entre dichas alternativas tenemos a los bacteriófagos que son los depredadores naturales de las bacterias; sin embargo, las investigaciones realizadas apuntan a su utilización como terapéuticos y no como promotores de crecimiento. Por tal motivo, el presente artículo de revisión se enfoca en discutir y proyectar el empleo de cocteles de bacteriófagos líticos como promotores de crecimiento en crianzas comerciales de pollos de engorde, gallinas de postura y codornices. Evaluando sus efectos sobre los parámetros productivos, su aplicación en agua de bebida y alimento, las estrategias de protección de fagos sobre los cambios de pH gastrointestinal y las altas temperaturas de peletización, estrategias contra la fago-resistencia, sus efectos sobre la microbiota intestinal, y el uso de autofagos versus los productos comerciales. Se concluye que la utilización óptima de bacteriófagos en avicultura comercial es mediante cocteles mixtos de autofagos líticos protegidos. Finalmente, se recomienda comparar el uso de cocteles mixtos de autofagos líticos con cocteles mixtos de fagos comerciales que existen en el mercado; adicionalmente, se debe evaluar la combinación de cocteles mixtos de autofagos líticos protegidos con otras alternativas como probióticos, prebióticos, aceites esenciales y ácidos orgánicos y comparar dicha combinación con el uso de antibióticos promotores de crecimiento

    Ambient Intelligence Systems for Personalized Sport Training

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    Several research programs are tackling the use of Wireless Sensor Networks (WSN) at specific fields, such as e-Health, e-Inclusion or e-Sport. This is the case of the project “Ambient Intelligence Systems Support for Athletes with Specific Profiles”, which intends to assist athletes in their training. In this paper, the main developments and outcomes from this project are described. The architecture of the system comprises a WSN deployed in the training area which provides communication with athletes’ mobile equipments, performs location tasks, and harvests environmental data (wind speed, temperature, etc.). Athletes are equipped with a monitoring unit which obtains data from their training (pulse, speed, etc.). Besides, a decision engine combines these real-time data together with static information about the training field, and from the athlete, to direct athletes’ training to fulfill some specific goal. A prototype is presented in this work for a cross country running scenario, where the objective is to maintain the heart rate (HR) of the runner in a target range. For each track, the environmental conditions (temperature of the next track), the current athlete condition (HR), and the intrinsic difficulty of the track (slopes) influence the performance of the athlete. The decision engine, implemented by means of (m; s)-splines interpolation, estimates the future HR and selects the best track in each fork of the circuit. This method achieves a success ratio in the order of 80%. Indeed, results demonstrate that if environmental information is not take into account to derive training orders, the success ratio is reduced notably.Ministerio de Educación y Ciencia; DEP2006-56158-C03-01/02/03Ministerio de Educación y Ciencia; TEC2007-67966 -01/02/TCM CON-PARTE-1/2Ministerio de Industria, Turismo y Comercio ; TSI-020301-2008-16 ELISAMinisterio de Industria, Turismo y Comercio ; TSI-020301-2008-2 PIRAmID

    The presence of peat and variation in tree species composition are under different hydrological controls in Amazonian wetland forests

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    This research was funded by the Gordon and Betty Moore Foundation, through grant #5349 ‘Monitoring protected areas in Peru to increase forest resilience to climate change’, and NERC standard grant ‘Carbon Storage in Amazonian Peatlands: Distribution and Dynamics’(NE/R000751/1).The peat-forming wetland forests of Amazonia are characterised by high below-carbon stocks and supply fruit, fibres and timber to local communities. Predicting the future of these ecosystem services requires understanding how hydrological conditions are related to tree species composition and the presence, or absence, of peat. Here, we use continuous measurements of water table depth over 2.5 years and manual measurements of pore-water pH and electrical conductivity to understand the ecohydrological controls of these variables across the large peatland complex in northern Peruvian Amazonia. Measurements were taken in permanent forest plots in four palm swamps, four seasonally flooded forests and four peatland pole forests. All trees ≥10 cm diameter were also measured and identified in the plots to assess floristic composition. Peat occurs in eight of these twelve sites; three seasonally flooded forests and one palm swamp are not associated with peat. Variation in tree species composition among forest types was linked to high flood levels (maximum flooding height) and pH: seasonally flooded forests experience high flood levels (up to 3.66 m from the ground surface) and have high pH values (6?7), palm swamps have intermediate flood levels (up to 1.34 m) and peatland pole forests experience shallow flooding (up to 0.28 m) and have low pH (4). In contrast, the presence of peat was linked to variation in maximum water table depth (ie the depth to which the water table drops below the ground surface). Surface peat is found in all forest types where maximum water table depth does not fall >0.55 m below the ground surface at any time. Peat formation and variation in tree species composition therefore have different ecohydrological controls. Predicted increases in the frequency and strength of flooding events may alter patterns of tree species composition, whereas increases in drought severity and declines in minimum river levels may pose a greater risk to the belowground carbon stores of these peatland ecosystems.Publisher PDFPeer reviewe

    Nueva base de datos de precipitaciones y temperaturas para Extremadura en el periodo (1989-2018)

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    Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]Se ha elaborado una nueva base de datos de precipitaciones medias mensuales y temperaturas máximas y mínimas medias mensuales, con la que se han analizado los datos de 142 estaciones meteorológicas obtenidos de la Agencia Estatal de Meteorología (AEMET) para el periodo (1989-2018). En este estudio se presentan los resultados de diferentes pruebas de homogeneización y relleno de 134, 172 y 176 series de temperaturas y precipitaciones provenientes de las estaciones ubicadas en la región de Extremadura. Para ello, se realizó un primer control de calidad de los datos cumpliendo con los requisitos de la Organización Meteorológica Mundial (OMM) y las recomendaciones indicadas por el Real Instituto Meteorológico de los Países Bajos (KNMI). Posteriormente se llevó a cabo la homogeneización de las series utilizando el software Climatol, en el que se han implementado diferentes funciones que permiten depurar los datos a través de un análisis de los valores atípicos y de la homogeneidad, así como la completación de las lagunas de las series. Los análisis confirman la obtención de unos niveles de depuración de los datos muy altos, confiables y de buena calidad; obteniendo así una nueva base de datos para posteriores estudios climáticos.[EN]A new database of monthly average rainfall and monthly average maximum and minimum temperatures has been developed, with which data from 142 weather stations obtained from the Agencia Estatal de Meteorología (AEMET) for the period (1989-2018) have been analysed. This study presents the results of different homogenisation and backfilling tests of 134, 172 and 176 temperature and precipitation series from stations located in the region of Extremadura. For this purpose, a first quality control of the data was carried out in compliance with the requirements of the World Meteorological Organisation (WMO) and the recommendations indicated by the Royal Netherlands Meteorological Institute (KNMI). Subsequently, the series were homogenised using Climatol software, in which different functions have been implemented to clean the data through an analysis of outliers and homogeneity, as well as filling in the gaps in the series. The analyses confirm the achievement of very high, reliable and good quality data cleaning levels, thus obtaining a new database for further climate studies.Esta investigación fue financiada por la Junta de Extremadura y el Fondo Europeo de Desarrollo Regional (FEDER) a través de la ayuda al grupo de investigación Alcántara (TIC008), GR21006, y el Proyecto IB18001 “Análisis y modelización del impacto del cambio climático sobre la distribución de zonas vitícolas en Extremadura”
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