Sinking of light intruders in a shaken granular bed

We present an experimental study of the displacement of a light intruder immersed in a vibrated granular bed. Using high speed video we resolve the motion, during one cycle of oscillation, of a cylindrical object inside a Plexiglas box partially filled with grains. We report experimental evidence that, in the absence of convection, at least two forces are behind the intruder’s motion: an air drag force—due to the airflow through the granular bed—and a buoyancy force produced by an air-mediated granular fluid

Experimental study of a TLP offshore floating wind turbine

Tank testing in a wind and wave environment is a key part of the design process for the development of an offshore floating wind turbine. The current paper describes an extensive experiment campaign carried out at the Kelvin Hydrodynamics Laboratory at the University of Strathclyde to determine the hydrodynamic performance of the Iberdrola TLPWIND offshore floating wind turbine with the NREL 5MW reference turbine over a range of environmental conditions. Tests were carried out for 70m water depth and the deployment area selected as off Aberdeen, North Sea. The campaign included free oscillation tests, tests in regular waves and irregular waves, and additionally examined failure and accidental load cases

FPGA acceleration using high-level languages of a Monte-Carlo method for pricing complex options

This is the author’s version of a work that was accepted for publication in Journal of Systems Architecture. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Systems Architecture, 59, 3 (2013) DOI: 10.1016/j.sysarc.2013.01.004In this paper we present an FPGA implementation of a Monte-Carlo method for pricing Asian options using Impulse C and floating-point arithmetic. In an Altera Stratix-V FPGA, a 149x speedup factor was obtained against an OpenMP-based solution in a 4-core Intel Core i7 processor. This speedup is comparable to that reported in the literature using a classic HDL-based methodology, but the development time is significantly reduced. Additionally, the use of a HLL-based methodology allowed us to implement a high-quality Gaussian random number generator, which produces more precise results than those obtained with the simple generators usually present in HDL-based designs

Spatial variability of soil chemical properties and its effect on crop yields: a case study in maize (zea mays l.) on the bogota plateau

To evaluate the effect of soil chemical properties on the crop yield of corn, in the context of site-specific fertilization, it was characterized the spatio-temporal variability of these properties and crop yield in a lot at the Centro Agropecuario Marengo of the Universidad Nacional de Colombia (Mosquera, Colombia). Using a systematic sampling grid of 32 points (25 x 25 m), soil samples were taken before crop sowing and 60 days after sowing (das) to determine soil pH, N (%); Ca, K, Mg, Na, Al, H (cmol+ kg-1), P, Cu, Fe, Mn, Zn and B (mg kg-1). At 162 das, harvest and yield components were evaluated by site. The data was processed using multivariate procedures, descriptive analysis and geostatistical analysis. Emergent properties were obtained from the original chemical variables using principal component analysis (PCA); these new variables were evaluated using geostatistical analysis to show spatial distribution and its correlation with crop yield. The PCA allowed the finding of three patterns of spatial variability in the soil corresponding to the variables related to soil fertility OC, Ca, Mg, K, CIC and B, the availability of nutrients by soil redox potential, and the variability associated with salinity explained by the Na content and soil electrical conductivity. The first group of variables largely explains the spatial variability of crop yield of corn

Análisis de islas de calor por medio de imágenes satelitales y sistemas de información geográficos en el área urbana de la Sabana de Bogotá

In this investigation all data related to Land surface temperature (LST) collected from  satellite Landsat 8 was compared to temperature data collected from surface stations located in Sabana de Bogotá, to identify urban heat islands. It was developed a crop in the study area of satellite image in order to processing spectrum bands 10, 4 and 5, using a Land surface Temperature algorithm to collect the satellite mapping of the surface temperature. At the same time, this data was analyzed as statistically as spatially considering the distance and elevation of the stations interpolating them with Cokriging’s method and the ArcGIS 10.3® Software, detecting spatially the geometry of the islands in high urbanization zones, getting the Pixel temperature and comparing it to surface station data finding differences between temperature in urban zones commonly with more vegetation and the two methods used for this study.En esta investigación, los datos relacionados con la temperatura superficial (LST) recopilados del satélite Landsat 8 se compararon con los datos de temperatura seleccionados de las estaciones de superficie, ubicadas en la sabana de Bogotá, para identificar islas de calor urbanas. Se recortó el área de estudio de la imagen satelital para procesar las bandas del espectro 10, 4 y 5, usando un algoritmo de temperatura superficial para recolectar el mapeo satelital. Al mismo tiempo, estos datos se analizaron estadísticamente como espacialmente considerando la distancia y la elevación de las estaciones interpolando con el método de Cokriging y el software ArcGIS 10.3®, detectando espacialmente la geometría de las islas en zonas de alta urbanización, obteniendo la temperatura de píxeles y comparándolo con los datos de la estación de superficie, encontrando diferencias entre la temperatura en zonas urbanas comúnmente con más vegetación y los dos métodos utilizados para este estudio

Consultoría integral en una escuela preparatoria particular incorporada a la Universidad de Guadalajara en el Municipio de Tlaquepaque

ITESO, A.C

Methodological approaches to assess climate vulnerability and cumulative impacts on coastal landscapes

Material complementario: https://www.frontiersin.org/articles/10.3389/fclim.2022.1018182/full#supplementary-materialNatural and human-induced hazards and climatic risks threaten marine and coastal ecosystems worldwide, with severe consequences for these socio-ecological systems. Therefore, assessing climate vulnerability (exposure, sensitivity and adaptive capacity) and the cumulative environmental impacts of multiple hazards are essential in coastal planning and management. In this article, we review some approaches used in climate vulnerability assessment and marine and coastal cumulative environmental impacts to learn about state-of-the-art on the subject. Besides, we qualitatively evaluated the climatic vulnerability of five coastal regions of Venezuela using the IPCC concept of Reasons for Concern (RFCs) to determine their level of climatic exposure. We also assessed the cumulative environmental impact of multiple stressors on marine and terrestrial ecosystems using a well-known impact assessment method partially modified to explore the feasibility of this model in data-poor areas. However, we found no standardization of the methodologies used in evaluating Coastal Climate Vulnerability or Cumulative Environmental Impacts in coastal landscapes or frameworks that operationally link them with socioecological systems. Most studied coastal regions are at risk from at least three RFCs, loss of unique ecosystems (RFC1), risks associated with extreme events (RFC2) and risks associated with global aggregate impacts (RFC4). Furthermore, the assessment showed that areas with accumulated impact cover about 10 percent ranging from moderate to high in urban areas, growth zones, industrial oil settlements, port areas and aquaculture areas with fishing activity. Moreover, areas with moderate to low cumulative impact cover half of the study area, dominated by uninhabited regions and vegetation of the thorny scrub and coastal grassland types. Therefore, we consider it essential to implement regional climate risk management that incorporates these assessments into the ordinance in countries that are particularly vulnerable to climate change, such as Venezuela, which has an extensive line of low-lying coastlines (where 60% of the country’s population lives) and coastal regions with harsh climates and poor economic conditions. Finally, we present the scope and limitations of implementing these evaluations and highlight the importance of incorporating them into regional strategies for adaptation to climate change

Radio detections towards unidentified variable EGRET sources

Context. A considerable fraction of the -ray sources discovered with the Energetic Gamma-Ray Experiment Telescope (EGRET) remain unidentified. The EGRET sources that have been properly identified are either pulsars or variable sources at both radio and gamma-ray wavelengths. Most of the variable sources are strong radio blazars. However, some low galactic-latitude EGRET sources, with highly variable -ray emission, lack any evident counterpart according to the radio data available until now. Aims. The primary goal of this paper is to identify and characterise the potential radio counterparts of four highly variable -ray sources in the galactic plane through mapping the radio surroundings of the EGRET confidence contours and determining the variable radio sources in the field whenever possible. Methods. We have carried out a radio exploration of the fields of the selected EGRET sources using the Giant Metrewave Radio Telescope (GMRT) interferometer at 21 cm wavelength, with pointings being separated by months. Results. We detected a total of 151 radio sources. Among them, we identified a few radio sources whose flux density has apparently changed on timescales of months. Despite the limitations of our search, their possible variability makes these objects a top-priority target for multiwavelength studies of the potential counterparts of highly variable, unidentified gamma-ray sources.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Response of sugarcane (Saccharum officinarum) to organic fertilizer in northern Belize

Among the most productive activities in northern Belize is sugar cane; as a result, it is a livelihood and income base for many Belizeans who depend on it. However, the low productivity has been an important factor since it has limited the production yield due to high costs of inputs such as synthetic chemical fertilizers, pesticides, among others. Also, due to its intensive application, it has caused a problem in sustainability between the soil, crops and the environment. The objective of this study was to evaluate the response of sugarcane to organic fertilization in northern Belize. The work consisted of a completely randomized experimental design of 10 treatments, made up of the control (without fertilization), synthetic chemical fertilization, bokashi, bovine biol, and their combinations. The variables evaluated were: Diameter, longitude, and stem weight, maturity index, number of dry leaves, weight of dry leaves, green tops, plant weight and plant longitude. The treatment that obtained the best result was treatment ten (T10, 3 t edaphic bokashi + 2 % foliar biol). It also obtained the highest yield of tons per hectare (t ha-1) with 330; likewise, higher maturity index with 89.9 %.Objective: To provide an ecological alternative for sugarcane producers in northern Belize evaluating the response of the crop to organic fertilizer (bovine biol and bokashi). Design/Methodology/Approach: Ten treatments with different doses and combinations of bokashi and bovine manure-based biol were applied in a crop of the sugarcane variety B79-474 in the northern region of Belize. Results: The combination of 3 t ha-1 of bokashi applied to the soil and 2% biol applied to the leaves recorded the best sugarcane yields, with an average weight of 2.0 kg per processable stalk. Study Limitations/Implications: Bokashi production involves the use of large amounts of manure, which are difficult to transport and handle with simple tools. Findings/Conclusions: The sugarcane variety B79-474 had a positive response to organic fertilizer (average yield: 2.0 kg per stalk and 330 t ha-1 of cane), applying 3 t ha-1 of bokashi to the soil and 2 % biol to the leaves

Nanointegracion: obtención controlada de nanoestructuras de óxido de grafeno reducido interconectadas en áreas macroscópicamente extendidas mediante la técnica de Langmuir Blodgett

El objetivo del presente trabajo es obtener películas delgadas de óxido de grafeno (GO) empleando la técnica de Langmuir-Blodgett (L-B) y posteriormente producir la reducción de la película, analizando distintos métodos, para obtener óxido de grafeno reducido (rGO). Con el objetivo de caracterizar als muestras de GO y rGO, las mismas fueron estudiadas por microscopía de fuerza atómica (AFM), micro-Raman y espectroscopía fotoelectrónica de rayos X (XPS) con resolución espacial nanométrica. Se realizaron además medidas de conductividad tanto a escala macro como nanométrica utilizando una estación de prueba y un nanomanipulador acoplado a un equipo de microscopía electrónica de barrido (SEM). Finalmente se correlacionaron el estado químico, la estructura y los defectos presentes en las películas delgadas de rGO con sus propiedades de transporte.El GO fue sintetizado mediante el método de Hummers [1], y se depositó sobre Si(100) empleando la técnica de L-B. El aspecto de los depósitos fue analizado mediante SEM. El espesor de las láminas de GO y rGO se estudió mediante AFM encontrándose para una lámina de rGO un espesor de 1,3±0,1nm, que corresponde al valor esperado para una única lámina de óxido de grafeno. Del análisis de los espectros Raman se puede apreciar una disminución de la banda D asociada a sitios defectuosos de la red [2] mientras que los resultados de XPS realizados in-situ durante un tratamiento térmico en ultra alto vacío permitieron cuantificar la reducción del material e identificar las especies químicas presentes en cada muestra. De acuerdo a las medidas de conductividad, las películas delgadas poseen un comportamiento semiconductor hasta que son reducidas a temperaturas en UHV, alcanzando entonces un carácter óhmico con una elevada conductividad del orden de 105 S/m, la mayor reportada hasta el momento en la literatura [3,4] para compuestos del tipo del rGO.El conjunto de datos experimentales demuestra por una parte la posibilidad de realizar depósitos controlados de GO por L-B y por otro lado, a partir de los resultados de caracterizaciones estructurales y espectroscópicas obtenidos, la eficiencia del proceso de reducción térmico para producir rGO conductor con baja densidad de defectos y una alta relación C/O. Este método de producción tiene gran potencial debido a que abre la posibilidad de sintetizar de forma controlada desde monocapas hasta multicapas de materiales del tipo de los grafenos con propiedades de transporte controladas tanto como aislante o como conductor.Facultad de Ciencias Exacta