Argonne National Laboratory

Lemont, Illinois, United States

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Division of Mathematics and Computer Science
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Division of Chemical Sciences and Engineering
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    ABSTRACT: We analyze the relationship between the noise level of a function and the accuracy and reliability of derivatives and difference estimates. We derive and empirically validate measures of quality for both derivatives and difference estimates. Using these measures, we quantify the accuracy of derivatives and differences in terms of the noise level of the function. An interesting observation based on these results is that the derivative of a function is not likely to have working precision accuracy for functions with modest levels of noise.
    Journal of Computational Physics. 01/2014; 273:268–277.
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    ABSTRACT: Recent technological advances in genomics now allow producing biological data at unprecedented tera- and petabyte scales. Yet, the extraction of useful knowledge from this voluminous data presents a significant challenge to a scientific community. Efficient mining of vast and complex data sets for the needs of biomedical research critically depends on seamless integration of clinical, genomic, and experimental information with prior knowledge about genotype-phenotype relationships accumulated in a plethora of publicly available databases. Furthermore, such experimental data should be accessible to a variety of algorithms and analytical pipelines that drive computational analysis and data mining. Translational projects require sophisticated approaches that coordinate and perform various analytical steps involved in the extraction of useful knowledge from accumulated clinical and experimental data in an orderly semiautomated manner. It presents a number of challenges such as (1) high-throughput data management involving data transfer, data storage, and access control; (2) scalable computational infrastructure; and (3) analysis of large-scale multidimensional data for the extraction of actionable knowledge.We present a scalable computational platform based on crosscutting requirements from multiple scientific groups for data integration, management, and analysis. The goal of this integrated platform is to address the challenges and to support the end-to-end analytical needs of various translational projects.
    Advances in experimental medicine and biology 01/2014; 799:39-67.
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    ABSTRACT: An essentially universal assumption of chemical kinetics is that bimolecular reactions only occur between reactants of rovibrational energy described by a Boltzmann (thermal) distribution. Given that the O2 mole fraction is roughly 20% under nearly all relevant low-temperature combustion situations, there is significant potential for molecules to undergo reactive collisions with O2 on the same time scale as the energy-transferring collisions necessary to achieving a Boltzmann distribution. Within the context of low-temperature combustion, this phenomenon conceivably gives rise to an entirely non-Boltzmann sequence involving multiple reactions of fuel-derived radicals with O2 to produce multiple OH radicals. Given the complex interplay among simultaneous internal isomerizations, energy-transferring collisions, dissociations and reactive collisions across multiple reaction surfaces, estimating the extent of deviations from conventional thermal assumptions is not straightforward. A novel methodology is presented for coupling multiple master equations and deriving effective phenomenological rate constants for thermal sets of reactants to thermal sets of products in chemically activated sequences that proceed across multiple reaction surfaces. The methodology is used to establish a better understanding of the nature of non-Boltzmann reactant distribution effects and quantify their magnitude. As a case study, we implement the methodology to explore the effect of non-Boltzmann reactants on product branching fractions of the QOOH* + O2 reaction from n-propyl oxidation as well as its associated dependence with O2 mole fraction, temperature, and pressure. While it appears that the effect of non-Boltzmann reaction sequences will be considerably smaller at higher pressures (at least for propane), it appears that consideration of non-Boltzmann reaction sequences is likely required for interpretations of experimental measurements commonly used to investigate the R + O2 and QOOH + O2 reactions central to engine-relevant ignition behavior. With regard to observable signatures of these effects in experiments, the presence of a stronger-than-usual O2 mole fraction dependence may be a likely indicator of non-Boltzmann behavior.
    Proceedings of the Combustion Institute 01/2014;

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Top publications last week by downloads

 
Second International Conference on e-Science and Grid Technologies (e-Science 2006), 4-6 December 2006, Amsterdam, The Netherlands; 01/2006
302 Downloads
 
Proceedings of the Winter Simulation Conference, WSC 2007, Washington, DC, USA, December 9-12, 2007; 01/2007
114 Downloads

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