39 research outputs found
Developing a Series of AI Challenges for the United States Department of the Air Force
Through a series of federal initiatives and orders, the U.S. Government has
been making a concerted effort to ensure American leadership in AI. These broad
strategy documents have influenced organizations such as the United States
Department of the Air Force (DAF). The DAF-MIT AI Accelerator is an initiative
between the DAF and MIT to bridge the gap between AI researchers and DAF
mission requirements. Several projects supported by the DAF-MIT AI Accelerator
are developing public challenge problems that address numerous Federal AI
research priorities. These challenges target priorities by making large,
AI-ready datasets publicly available, incentivizing open-source solutions, and
creating a demand signal for dual use technologies that can stimulate further
research. In this article, we describe these public challenges being developed
and how their application contributes to scientific advances
Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 41 (2010): 812-821, doi:10.1016/j.orggeochem.2010.05.003.Hydraulic connectivity of petroleum reservoirs represents one of the biggest uncertainties for
both oil production and petroleum system studies. Here, a geochemical analysis involving bulk and
detailed measures of crude oil composition is shown to constrain connectivity more tightly than is
possible with conventional methods. Three crude oils collected from different depths in a single well
exhibit large gradients in viscosity, density, and asphaltene content. Crude oil samples are collected
with a wireline sampling tool providing samples from well‐defined locations and relatively free of
contamination by drilling fluids; the known provenance of these samples minimizes uncertainties in the
subsequent analysis. The detailed chemical composition of almost the entire crude oil is determined by
use of comprehensive two‐dimensional gas chromatography (GC×GC) to interrogate the nonpolar
fraction and negative ion electrospray ionization Fourier transform ion cyclotron resonance mass
spectrometry (ESI FT‐ICR MS) to interrogate the polar fraction. The simultaneous presence of 25‐
norhopanes and mildly altered normal and isoprenoid alkanes is detected, suggesting that the reservoir
has experienced multiple charges and contains a mixture of oils biodegraded to different extents. The
gradient in asphaltene concentration is explained by an equilibrium model considering only gravitational
segregation of asphaltene nanoaggregates; this grading can be responsible for the observed variation in
viscosity. Combining these analyses yields a consistent picture of a connected reservoir in which the
observed viscosity variation originates from gravitational segregation of asphaltene nanoaggregates in a
crude oil with high asphaltene concentration resulting from multiple charges, including one charge that
suffered severe biodegradation. Observation of these gradients having appropriate magnitudes
suggests good reservoir connectivity with greater confidence than is possible with traditional techniques
alone.The mass spectrometry work was
supported by the NSF Division of Materials Research through DMR‐06‐54118, and the State of Florida
Responses of diversity and dominance to grazing. A global analysis
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Change in dominance determines herbivore effects on plant biodiversity.
Herbivores alter plant biodiversity (species richness) in many of the world's ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis-that herbivore-induced changes in the competitive environment determine the response of plant biodiversity to herbivory irrespective of productivity. Under this hypothesis, when herbivores reduce the abundance (biomass, cover) of dominant species (for example, because the dominant plant is palatable), additional resources become available to support new species, thereby increasing biodiversity. By contrast, if herbivores promote high dominance by increasing the abundance of herbivory-resistant, unpalatable species, then resource availability for other species decreases reducing biodiversity. We show that herbivore-induced change in dominance, independent of site productivity or precipitation (a proxy for productivity), is the best predictor of herbivore effects on biodiversity in grassland and savannah sites. Given that most herbaceous ecosystems are dominated by one or a few species, altering the competitive environment via herbivores or by other means may be an effective strategy for conserving biodiversity in grasslands and savannahs globally
Deep Underground Neutrino Experiment (DUNE), Far Detector Technical Design Report, Volume I Introduction to DUNE
International audienceThe preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay—these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. The Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. This TDR is intended to justify the technical choices for the far detector that flow down from the high-level physics goals through requirements at all levels of the Project. Volume I contains an executive summary that introduces the DUNE science program, the far detector and the strategy for its modular designs, and the organization and management of the Project. The remainder of Volume I provides more detail on the science program that drives the choice of detector technologies and on the technologies themselves. It also introduces the designs for the DUNE near detector and the DUNE computing model, for which DUNE is planning design reports. Volume II of this TDR describes DUNE's physics program in detail. Volume III describes the technical coordination required for the far detector design, construction, installation, and integration, and its organizational structure. Volume IV describes the single-phase far detector technology. A planned Volume V will describe the dual-phase technology
DUNE Offline Computing Conceptual Design Report
International audienceThis document describes Offline Software and Computing for the Deep Underground Neutrino Experiment (DUNE) experiment, in particular, the conceptual design of the offline computing needed to accomplish its physics goals. Our emphasis in this document is the development of the computing infrastructure needed to acquire, catalog, reconstruct, simulate and analyze the data from the DUNE experiment and its prototypes. In this effort, we concentrate on developing the tools and systems thatfacilitate the development and deployment of advanced algorithms. Rather than prescribing particular algorithms, our goal is to provide resources that are flexible and accessible enough to support creative software solutions as HEP computing evolves and to provide computing that achieves the physics goals of the DUNE experiment
The DUNE Far Detector Vertical Drift Technology, Technical Design Report
International audienceDUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered. This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals