A hierarchic task-based programming model for distributed heterogeneous computing

Distributed computing platforms are evolving to heterogeneous ecosystems with Clusters, Grids and Clouds introducing in its computing nodes, processors with different core architectures, accelerators (i.e. GPUs, FPGAs), as well as different memories and storage devices in order to achieve better performance with lower energy consumption. As a consequence of this heterogeneity, programming applications for these distributed heterogeneous platforms becomes a complex task. Additionally to the complexity of developing an application for distributed platforms, developers must also deal now with the complexity of the different computing devices inside the node. In this article, we present a programming model that aims to facilitate the development and execution of applications in current and future distributed heterogeneous parallel architectures. This programming model is based on the hierarchical composition of the COMP Superscalar and Omp Superscalar programming models that allow developers to implement infrastructure-agnostic applications. The underlying runtime enables applications to adapt to the infrastructure without the need of maintaining different versions of the code. Our programming model proposal has been evaluated on real platforms, in terms of heterogeneous resource usage, performance and adaptation.This work has been supported by the European Commission through the Horizon 2020 Research and Innovation program under contract 687584 (TANGO project) by the Spanish Government under contract TIN2015-65316 and grant SEV-2015-0493 (Severo Ochoa Program) and by Generalitat de Catalunya under contracts 2014-SGR-1051 and 2014-SGR-1272.Peer ReviewedPostprint (author's final draft

The Carbon Intensity of NGV C8 Trucks

Natural gas vehicles have been favored by U.S. air quality agencies for the cleaner burning properties of natural gas. However, the climate consequences of a switch to natural gas vehicles for long distance, heavy-duty applications has been less clear. The radioactive forcings of short-lived methane leakage must be weighed against any long term benefits of emitting less CO2. The scientific literature reports a variety of results and conclusions, thus policy makers often find it hard to make science-based, sound decision-making. But there is inherent natural variability in the system and virtually any result can be justified based on a given choice of input values. Some scholars deal with this variability with probabilistic distributions of inputs to produce probabilistic distributions of results. But this treatment of uncertainty might not resound with decision makers, who might prefer the simplicity of one single estimate. In this study, we attempt to tackle and communicate uncertainty in a simplified way in which a transparent base case scenario is modified one input at a time to determine the distinct parameters that are critical to assessing the climate impact of natural gas as a transportation fuel. Instead of focusing on a specific number, this analysis shows what makes a natural gas fuel a better option versus a bad option, so policy makers and agencies can focus on promoting these best practices among the interested parties. We utilize Argonne’s GREET1 2014 model to test sensitivities for the life cycle carbon intensity of natural gas versus diesel fuel under a range of scenarios for upstream and in vehicle methane leakage, fueling and storage technologies, and operational performance of various kinds of class 8 engines. We evaluate the relative importance of engine technology, natural gas fuel storage choice, upstream methane leakage (i.e., well-to-tank), and vehicle methane slip (i.e., tank-to-wheel). We find that: 1) Upstream methane leakage contributes between 7 and 11% and vehicle methane leakage (i.e., methane slip) contributes between 5 and 9% to the total carbon intensity of natural gas in long haul trucks; 2) Variability factors include whether natural gas fuel is stored as compressed (CNG) or liquefied (LNG) and whether a natural gas vehicle uses spark ignition or compression ignition. Natural gas engines typically being spark ignition, which are around 10% less efficient than compression ignition diesel engines; 3) If no efficiency penalty is assumed (as in the case of the currently out of market HPDI model), NGVs offer a climate advantage compared to diesel only if well-to-tank methane leakage remains under 5%; and 4) CNG storage is more sensitive to leakage than LNG storage. This analysis allows us to identify the most important strategies to reduce the carbon intensity of NGVs

The early phases of galaxy clusters formation in IR: coupling hydrodynamical simulations with GRASIL3D

We compute and study the infrared and sub-mm properties of high redshift ($z \gtrsim 1$) simulated clusters and proto-clusters. The results of a large set of hydro-dynamical zoom-in simulations including active galactic nuclei (AGN) feedback, have been treated with the recently developed radiative transfer code GRASIL-3D, which accounts for the effect of dust reprocessing in an arbitrary geometry. Here, we have slightly generalized the code to adapt it to the present purpose. Then we have post-processed boxes of physical size 2 Mpc encompassing each of the 24 most massive clusters identified at z=0, at several redshifts between 0.5 and 3, producing IR and sub-mm mock images of these regions and SEDs of the radiation coming out from them. While this field is in its infancy from the observational point of view, rapid development is expected in the near future thanks to observations performed in the far IR and sub-mm bands. Notably, we find that in this spectral regime our prediction are little affected by the assumption required by this post-processing, and the emission is mostly powered by star formation rather than accretion onto super massive black hole (SMBH). The comparison with the little observational information currently available, highlights that the simulated cluster regions never attain the impressive star formation rates suggested by these observations. This problem becomes more intriguing taking into account that the brightest cluster galaxies (BCGs) in the same simulations turn out to be too massive. It seems that the interplay between the feedback schemes and the star formation model should be revised, possibly incorporating a positive feedback mode.Comment: 14 pages, 11 figures, MNRAS in press. Minor editorial improvement

Tu sólo, Todos juntos, Respuesta Inmediata a los Alumnos que es la tutoría

Los nuevos Planes de Estudios incluyen apartados sobre las Tutorías, generalmente encaminadas hacia la adjudicación de un grupo de alumnos a un profesor Tutor/Mentor durante toda su vida universitaria. Sobre el papel queda bien, pero puede haber profesores que lo consideren “una labor más”, con el consiguiente abandono o paso a un segundo plano de este difícil quehacer, que además requiere bastante tiempo y dedicación. Consideramos que la labor del TUTOR queda poco definida. Podemos apoyarnos en la bibliografía existente sobre las tutorías, pero ninguna responde a las necesidades globales por lo que sería una misión del Centro, o mejor aún de la Institución, quienes recojan y elaboren el material adecuado para las necesidades de nuestra Universidad. Si no se logra organizar la Acción Tutorial en conjunto, habrá profesores que intenten cumplirla, sintiéndose muy solos en ocasiones, y habrá profesores que “pasen” porque no la consideran una labor propiamente académica

The Water Footprint of Fuel Ethanol

Biofuels (Le., biomass-derived fuels) play a key role in discussions in the United States about energy security, agriculture, taxes and the environment. Although their potential to reduce our dependence on foreign oil and to mitigate climate change is still being debated, biofuels constitute a renewable domestic resource, offer advantages to air quality improvement, and provide alternative revenue for agricultural producers. In 2007, Congress enacted the Energy Independence and Security Act (EISA), which mandates the production of 36 billion gallons per year (BGY) of biofuels by 2022, including 15 BGY of corn-derived ethanol. This large increase in demand for biofuels requires immediate consideration and mitigation of unintended environmental impacts. Specifically, there is concern that the potentially high water demand for biofuel production could result in added pressure to already scarce water resources across the country and become, in many cases, the main limiting factor to biofuel production. The extent of the impact created by different crops and across agricultural regions is unknown but could potentially be large. In addition, climate change could ameliorate or worsen the water footprint of biofuels through several mechanisms. First, it could either reduce or increase rainfall and water availability. Secondly, water use by crops will change as a result of the combination of several factors influenced by climate change (notably temperature, precipitation and C02 concentration in the air), which interact in complex ways. Finally, climate changes will be markedly regional and biofuels production is also highly concentrated in one particular region of the United States, potentially magnifying the effects on water resources of large scale production. To answer these important questions, we calculated the water requirements for biofuel production from mUltiple cash crops (i.e., corn, soybean, switchgrass, sorghum, potatoes, and sugarbeet), taking into consideration the region they are currently grown. This is done through a life cycle analysis (LCA) methodology and based on existing US Department of Agriculture (USDA) and industry statistics. We also estimated the effects of climate change in the water demand of corn, the most prominent biofuel crop, using a large-scale distributed agricultural model and projections of climate change from coupled General Circulation Models (GCMs). Climate projections from five different models were used to include a wide range of future climate scenarios. This approach is necessary given the large differences in projected precipitation that exist between different climate models. The magnitude of projected increase in water requirements varied across the five simulations but the trend was consistently upwards in all of them. Overall, this thesis will enhance decision making by contributing with a tool that can provide spatially distributed projections of water requirements for biofuel crop agriculture. The location of future biofuel crop acreage is unknown at this time, which precludes accurate discernment of where and to what extent water shortages are likely to occur. Nevertheless, model simulations underscore the importance to consider irrigation requirements and water resources availability prior to selecting biofuel crops and where to grow them to avoiding straining regional water resources and jeopardizing future biofuel production. Specifically, our analyses show that the consumptive water demands associated with biofuel crop agriculture ranges from 500 to 4,000 liters of water for liter of fuel ethanol produced under current climatic conditions. Simulations with corn showed that by mid century corn crops in traditionally irrigated areas of the High Plains might require significantly more water (up to 40% in some areas) and that biofuels production now taking place in traditionally rainfed areas of the Midwest might require irrigated water supplies, potentially placing a major strain on water resources in that region, if not analyzed and managed properly. This analysis suggests that u.S. biofuels policy will have to be adjusted in the coming years to avoid exacerbating the substantial pressures that climate change are expected to have on certain regions of the United States and on national food production. In particular, the Ogallala Aquifer, the main source of irrigation water in the High Plains, is already experiencing significant water table drops and could be significantly threatened by a continuation of current biofuels policy in the context of projected climate change outcomes

Los nuevos grados: ¿Pirámide o Torre?

De las dos estructuras de conocimiento posibles “pirámide” y “torre”, nuestras escuelas de ingeniería se han decido sin ningún género de duda por la segunda, es decir, aquella que consiste en adquirir un conocimiento especializado desde el inicio para poder llegar a la máxima “altura” posible. Esto constituye un riesgo que, un conocimiento tipo “torre” por su reducida base y elevada altura implica que, una pequeña desviación necesaria para la acomodación del bagaje de conocimientos adquiridos al los nuevos retos profesionales, produciría el “pandeo” y consiguiente colapso de esa estructura. Por el contrario, una estructura piramidal, al tener una amplia base de conocimiento permite la modificación de la situación sin perder estabilidad

The Effect of kaolin properties on their behaviour in ceramic processing as illustrated by a range of kaolins from the Santa Cruz and Chubut Provinces, Patagonia (Argentina)

The Patagonian kaolins offer a wide set of origin of deposits, composition, mineral processing and ceramic properties, giving a rare opportunity for investigating the interdependence of mineralogy, chemical composition, particle size distribution, texture, and surface activity with their technological behaviour in sanitaryware and porcelain stoneware production. Plasticity is strictly dependent on surface activity, <2 micron fraction and expandable clay minerals; slip rheology is affected by soluble salts and expandable clay minerals, but also by high specific surface or tubular halloysite. Kaolinite/halloysite play an opposite role versus smectite/interstratified I/S in slip casting and tile pressing: the former allow faster casting rates, while the latter improve powder flowability and mechanical strength. Kaolinite and quartz are beneficial for drying behaviour while high surface activity or expandable clay minerals increase significantly drying sensitivity. Firing behaviour is mainly affected by minor components supplying "fluxing" (i.e. iron, alkali and alkaline-earth) oxides. A great deal of technological parameters seem to be reasonably predicted by the surface activity of clays and especially the Methylene Blue index, which is the most reliable, simple and economic method to predict and control the ceramic response of kaolins and ball clays

Galaxies going MAD: The Galaxy-Finder Comparison Project

With the ever increasing size and complexity of fully self-consistent simulations of galaxy formation within the framework of the cosmic web, the demands upon object finders for these simulations has simultaneously grown. To this extent we initiated the Halo Finder Comparison Project that gathered together all the experts in the field and has so far led to two comparison papers, one for dark matter field haloes (Knebe et al. 2011), and one for dark matter subhaloes (Onions et al. 2012). However, as state-of-the-art simulation codes are perfectly capable of not only following the formation and evolution of dark matter but also account for baryonic physics (e.g. hydrodynamics, star formation, feedback) object finders should also be capable of taking these additional processes into consideration. Here we report on a comparison of codes as applied to the Constrained Local UniversE Simulation (CLUES) of the formation of the Local Group which incorporates much of the physics relevant for galaxy formation. We compare both the properties of the three main galaxies in the simulation (representing the MW, M31, and M33) as well as their satellite populations for a variety of halo finders ranging from phase-space to velocity-space to spherical overdensity based codes, including also a mere baryonic object finder. We obtain agreement amongst codes comparable to (if not better than) our previous comparisons, at least for the total, dark, and stellar components of the objects. However, the diffuse gas content of the haloes shows great disparity, especially for low-mass satellite galaxies. This is primarily due to differences in the treatment of the thermal energy during the unbinding procedure. We acknowledge that the handling of gas in halo finders is something that needs to be dealt with carefully, and the precise treatment may depend sensitively upon the scientific problem being studied.Comment: 14 interesting pages, 17 beautiful figures, and 2 informative tables accepted for publication in MNRAS (matches published version