FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Hubbard, JA Brockmann, JE Dellinger, J Lucero, DA Sanchez, AL Servantes, BL AF Hubbard, J. A. Brockmann, J. E. Dellinger, J. Lucero, D. A. Sanchez, A. L. Servantes, B. L. TI Fibrous Filter Efficiency and Pressure Drop in the Viscous-Inertial Transition Flow Regime SO AEROSOL SCIENCE AND TECHNOLOGY LA English DT Article ID REYNOLDS-NUMBERS; SPHERICAL-PARTICLES; AEROSOL FILTRATION; IMPACTION; MOBILITY; DENSITY; CYLINDERS; MASS AB Fibrous filter pressure drop and aerosol collection efficiency were measured at low air pressures (0.2-0.8 atm) and high face velocities (5-19 m/s) to give fiber Reynolds numbers lying in the viscous-inertial transition flow regime (1-15). In this regime, contemporary filtration theory based on Kuwabara's viscous flow through an ensemble of fibers underpredicts single fiber impaction by several orders of magnitude. Streamline curvature increases substantially as air stream inertial forces become significant. Dimensionless pressure drop measurements followed the viscous-inertial theory of Robinson and Franklin (1972) rather than Darcy's linear pressure-velocity relationship. Sodium chloride and iron nano-agglomerate aerosols were tested to provide a comparison between particles of dissimilar densities and shape factors. Total filter efficiency collapsed when plotted against the particle Stokes number and fiber Reynolds number. Efficiencies were then modeled with an impactor type equation where the cutpoint Stokes number and a steepness parameter described data well in the sharply increasing portion of the curve (20%-80% efficiency). A minimum in collection efficiency was observed at small Stokes numbers and attributed to interception and diffusive effects. The cutpoint Stokes number was a linearly decreasing function of fiber Reynolds number. Single fiber efficiencies were calculated from total filter efficiencies and compared to contemporary viscous flow impaction theory (Stechkina et al. 1969), and numerical simulations of single fiber efficiencies from the literature. Existing theories underpredicted measured single fiber efficiencies, although comparison is problematic. The assumption of uniform flow conditions for each successive layer of fibers is questionable; thus, the common exponential relationship between single fiber efficiency and total filter efficiency may not be appropriate in this regime. C1 [Hubbard, J. A.; Brockmann, J. E.; Dellinger, J.; Lucero, D. A.; Sanchez, A. L.; Servantes, B. L.] Sandia Natl Labs, Albuquerque, NM 87185 USA. RP Hubbard, JA (reprint author), Sandia Natl Labs, POB 5800,MS 1135, Albuquerque, NM 87185 USA. EM jahubba@sandia.gov FU NNSA, Office of Nonproliferation RD [NA-22]; U.S. Department of Energy's National Nuclear Security Administration [DE-AC04-94AL85000] FX This work was funded by NNSA/NA-22, Office of Nonproliferation R&D. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. NR 31 TC 5 Z9 5 U1 2 U2 18 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 0278-6826 J9 AEROSOL SCI TECH JI Aerosol Sci. Technol. PY 2012 VL 46 IS 2 BP 138 EP 147 DI 10.1080/02786826.2011.616555 PG 10 WC Engineering, Chemical; Engineering, Mechanical; Environmental Sciences; Meteorology & Atmospheric Sciences SC Engineering; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 848PZ UT WOS:000297065900002 ER PT J AU Kuang, CA Chen, MD McMurry, PH Wang, J AF Kuang, Chongai Chen, Modi McMurry, Peter H. Wang, Jian TI Modification of Laminar Flow Ultrafine Condensation Particle Counters for the Enhanced Detection of 1 nm Condensation Nuclei SO AEROSOL SCIENCE AND TECHNOLOGY LA English DT Article ID ELECTRICAL MOBILITY; SIZE DISTRIBUTIONS; AEROSOL; NUCLEATION; MASS; NANOPARTICLES; CLUSTERS AB This paper describes simple modifications to thermally diffusive laminar flow ultrafine condensation particle counters (UCPCs) that allow detection of similar to 1 nm condensation nuclei with much higher efficiencies than have been previously reported. These non-destructive modifications were applied to a commercial butanol-based UCPC (TSI 3025A) and to a diethylene glycol-based UCPC (UMN DEG-UCPC). Size and charge dependent detection efficiencies using the modified UCPCs (BNL 3025A and BNL DEG-UCPC) were measured with high resolution mobility classified aerosols composed of NaCl, W, molecular ion standards of tetraalkyl ammonium bromide, and neutralizer-generated ions. With negatively charged NaCl aerosol, the BNL 3025A and BNL DEG-UCPC achieved detection efficiencies of 37% (90x increase over TSI 3025A) at 1.68 nm mobility diameter (1.39 nm geometric diameter) and 23% (8x increase over UMN DEG-UCPC) at 1.19 nm mobility diameter (0.89 nm geometric diameter), respectively. Operating conditions for both UCPCs were identified that allowed negatively charged NaCl and W particles, but not negative ions of exactly the same mobility size, to be efficiently detected. This serendipitous material dependence, which is not fundamentally understood, suggests that vapor condensation might sometimes allow for the discrimination between air "ions" and charged "particles." As a detector in a scanning mobility particle spectrometer (SMPS), a UCPC with this strong material dependence would allow for more accurate measurements of sub-2 nm aerosol size distributions due to the reduced interference from neutralizer-generated ions and atmospheric ions, and provide increased sensitivity for the determination of nucleation rates and initial particle growth rates. C1 [Kuang, Chongai; Wang, Jian] Brookhaven Natl Lab, Div Atmospher Sci, Upton, NY 11973 USA. [Chen, Modi; McMurry, Peter H.] Univ Minnesota, Dept Mech Engn, Minneapolis, MN 55455 USA. RP Wang, J (reprint author), Brookhaven Natl Lab, Div Atmospher Sci, Bldg 815E, Upton, NY 11973 USA. EM jian@bnl.gov RI Kuang, Chongai/E-4446-2013; Wang, Jian/G-9344-2011; McMurry, Peter/A-8245-2008 OI McMurry, Peter/0000-0003-1609-5131 FU US Department of Energy (DOE) (Office of Science, OBER) [DE-AC02-98CH10886]; US DOE [DE-FG-02-05ER63997] FX This work was supported by the US Department of Energy's (DOE) Atmospheric System Research Program (Office of Science, OBER) under contract DE-AC02-98CH10886 and by US DOE Grant Number DE-FG-02-05ER63997. NR 20 TC 22 Z9 22 U1 2 U2 21 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 0278-6826 J9 AEROSOL SCI TECH JI Aerosol Sci. Technol. PY 2012 VL 46 IS 3 BP 309 EP 315 DI 10.1080/02786826.2011.626815 PG 7 WC Engineering, Chemical; Engineering, Mechanical; Environmental Sciences; Meteorology & Atmospheric Sciences SC Engineering; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 848QP UT WOS:000297068500005 ER PT J AU Ahrens, J Debattista, K AF Ahrens, James Debattista, Kurt TI Guest Editor's Introduction: Special Section on the Eurographics Symposium on Parallel Graphics and Visualization (EGPGV) SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Editorial Material C1 [Ahrens, James] Los Alamos Natl Lab, Appl Comp Sci Grp, Los Alamos, NM 87545 USA. [Debattista, Kurt] Univ Warwick, Int Digital Lab, WMG, Coventry CV4 7AL, W Midlands, England. RP Ahrens, J (reprint author), Los Alamos Natl Lab, Appl Comp Sci Grp, Mail Stop B287, Los Alamos, NM 87545 USA. EM ahrens@lanl.gov; K.Debattista@warwick.ac.uk NR 0 TC 0 Z9 0 U1 1 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JAN PY 2012 VL 18 IS 1 BP 3 EP 4 PG 2 WC Computer Science, Software Engineering SC Computer Science GA 844UW UT WOS:000296775400003 ER PT J AU Howison, M Bethel, EW Childs, H AF Howison, Mark Bethel, E. Wes Childs, Hank TI Hybrid Parallelism for Volume Rendering on Large-, Multi-, and Many- Core Systems SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Article DE Volume visualization; parallel processing AB With the computing industry trending toward multi- and many- core processors, we study how a standard visualization algorithm, raycasting volume rendering, can benefit from a hybrid parallelism approach. Hybrid parallelism provides the best of both worlds: using distributed-memory parallelism across a large numbers of nodes increases available FLOPs and memory, while exploiting shared-memory parallelism among the cores within each node ensures that each node performs its portion of the larger calculation as efficiently as possible. We demonstrate results from weak and strong scaling studies, at levels of concurrency ranging up to 216,000, and with data sets as large as 12.2 trillion cells. The greatest benefit from hybrid parallelism lies in the communication portion of the algorithm, the dominant cost at higher levels of concurrency. We show that reducing the number of participants with a hybrid approach significantly improves performance. C1 [Howison, Mark] Brown Univ, Ctr Computat & Visualizat, Providence, RI 02912 USA. [Bethel, E. Wes; Childs, Hank] Univ Calif Berkeley, Lawrence Berkeley Lab, Visualizat Grp, Berkeley, CA 94720 USA. RP Howison, M (reprint author), Brown Univ, Ctr Computat & Visualizat, 94 Waterman St, Providence, RI 02912 USA. EM mhowison@brown.edu; ewbethel@lbl.gov; hchilds@lbl.gov OI Howison, Mark/0000-0002-0764-4090 FU Office of Science, Office and Advanced Scientific Computing Research, of the US Department of Energy (DOE) [DE-AC02-05CH11231]; Office of Science of the DOE [DE-AC02-05CH11231, DE-AC05-00OR22725] FX This work was supported by the Director, Office of Science, Office and Advanced Scientific Computing Research, of the US Department of Energy (DOE) under Contract No. DE-AC02-05CH11231 through the Scientific Discovery through Advanced Computing (SciDAC) program's Visualization and Analytics Center for Enabling Technologies (VACET). This research used resources of the National Center for Computational Sciences at Oak Ridge National Laboratory, which is supported by the Office of Science of the DOE under Contract No. DE-AC05-00OR22725. Additionally, preliminary results for this work were collected using resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the DOE under Contract No. DE-AC02-05CH11231. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing the GPU cluster Longhorn that contributed to the research results reported within this paper. NR 30 TC 14 Z9 15 U1 0 U2 12 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JAN PY 2012 VL 18 IS 1 BP 17 EP 29 DI 10.1109/TVCG.2011.24 PG 13 WC Computer Science, Software Engineering SC Computer Science GA 844UW UT WOS:000296775400005 PM 21282855 ER PT J AU Correa, CD Crnovrsanin, T Ma, KL AF Correa, Carlos D. Crnovrsanin, Tarik Ma, Kwan-Liu TI Visual Reasoning about Social Networks Using Centrality Sensitivity SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Article DE Social network visualization; centrality; sensitivity analysis; eigenvector and Markov importance ID CLIQUE IDENTIFICATION; VISUALIZATION; GRAPHS; ALGORITHM; SEARCH AB In this paper, we study the sensitivity of centrality metrics as a key metric of social networks to support visual reasoning. As centrality represents the prestige or importance of a node in a network, its sensitivity represents the importance of the relationship between this and all other nodes in the network. We have derived an analytical solution that extracts the sensitivity as the derivative of centrality with respect to degree for two centrality metrics based on feedback and random walks. We show that these sensitivities are good indicators of the distribution of centrality in the network, and how changes are expected to be propagated if we introduce changes to the network. These metrics also help us simplify a complex network in a way that retains the main structural properties and that results in trustworthy, readable diagrams. Sensitivity is also a key concept for uncertainty analysis of social networks, and we show how our approach may help analysts gain insight on the robustness of key network metrics. Through a number of examples, we illustrate the need for measuring sensitivity, and the impact it has on the visualization of and interaction with social and other scale-free networks. C1 [Correa, Carlos D.] Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. [Crnovrsanin, Tarik; Ma, Kwan-Liu] Univ Calif Davis, Davis, CA 95616 USA. RP Correa, CD (reprint author), Lawrence Livermore Natl Lab, Box 808,L-422, Livermore, CA 94551 USA. EM correac@llnl.gov; tecrnovrsanin@ucdavis.edu; ma@ucdavis.edu FU US National Science Foundation (NSF) [CCF-0811422, CCF-0808896, CCF-0938114, CCF-1025269] FX This work was sponsored in part by the US National Science Foundation (NSF) through grants CCF-0811422, CCF-0808896, CCF-0938114, and CCF-1025269. NR 44 TC 18 Z9 18 U1 0 U2 10 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JAN PY 2012 VL 18 IS 1 BP 106 EP 120 DI 10.1109/TVCG.2010.260 PG 15 WC Computer Science, Software Engineering SC Computer Science GA 844UW UT WOS:000296775400013 PM 22076488 ER PT J AU Shafii, S Dillard, SE Hlawitschka, M Hamann, B AF Shafii, Sohail Dillard, Scott E. Hlawitschka, Mario Hamann, Bernd TI The Topological Effects of Smoothing SO IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS LA English DT Article DE Volume visualization; visualization techniques and methodologies; smoothing ID CONTOUR TREES; DIMENSIONS; IMAGES AB Scientific data sets generated by numerical simulations or experimental measurements often contain a substantial amount of noise. Smoothing the data removes noise but can have potentially drastic effects on the qualitative nature of the data, thereby influencing its characterization and visualization via topological analysis, for example. We propose a method to track topological changes throughout the smoothing process. As a preprocessing step, we oversmooth the data and collect a list of topological events, specifically the creation and destruction of extremal points. During rendering, it is possible to select the number of topological events by interactively manipulating a merging parameter. The result that a specific amount of smoothing has on the topology of the data is illustrated using a topology-derived transfer function that relates region connectivity of the smoothed data to the original regions of the unsmoothed data. This approach enables visual as well as quantitative analysis of the topological effects of smoothing. C1 [Shafii, Sohail; Hamann, Bernd] Univ Calif Davis, Dept Comp Sci, Davis, CA 95616 USA. [Dillard, Scott E.] Pacific NW Natl Lab, Richland, WA 99352 USA. [Hlawitschka, Mario] Univ Leipzig, Inst Informat, Leipzig, Germany. RP Shafii, S (reprint author), Univ Calif Davis, Dept Comp Sci, 1 Shields Ave, Davis, CA 95616 USA. EM sohail.shafii@gmail.com; Scott.Dillard@pnl.gov; hlawitschka@informatik.uni-leipzig.de; hamann@cs.ucdavis.edu FU Materials Design Institute; UC Davis/Los Alamos National Laboratory Educational Research Collaboration (LANL) [25110-002-06]; UC; US National Science Foundation (NSF [CCF-0702817] FX This work was supported by the Materials Design Institute, funded by the UC Davis/Los Alamos National Laboratory Educational Research Collaboration (LANL Agreement No. 25110-002-06), and the UC Lab Fees Research Program Contingency Funds. In addition, this effort was supported by the US National Science Foundation (NSF) through grant CCF-0702817. We thank our colleagues from the Institute for Data Analysis and Visualization (IDAV), Department of Computer Science, UC Davis and Gunther Weber for providing code from his publication [41]. NR 43 TC 2 Z9 2 U1 0 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1077-2626 EI 1941-0506 J9 IEEE T VIS COMPUT GR JI IEEE Trans. Vis. Comput. Graph. PD JAN PY 2012 VL 18 IS 1 BP 160 EP 172 DI 10.1109/TVCG.2011.74 PG 13 WC Computer Science, Software Engineering SC Computer Science GA 844UW UT WOS:000296775400017 PM 21519107 ER PT J AU Hecht, F Kuate, R Tautges, T AF Hecht, Frederic Kuate, Raphael Tautges, Timothy TI Local transformations of hexahedral meshes of lower valence SO COMPUTATIONAL GEOMETRY-THEORY AND APPLICATIONS LA English DT Article DE Mesh adaptation; Quadrilateral; Hexahedron; Flipping ID CUBICAL POLYTOPES; COMPLEXES AB The modification of conforming hexahedral meshes is difficult to perform since their structure does not allow easy local refinement or un-refinement such that the modification does not go through the boundary. In this paper we prove that the set of hex flipping transformations of Bern et al. (2002) Ill is the only possible local modification on a geometrical hex mesh of valence less than five i.e., with less than five edges per vertex. We propose a new basis of transformations that can generate sequences of local modifications on hex meshes of valence less than six. For quadrilateral meshes, we show the equivalence between modifying locally the number of quads on a mesh and the number of its internal vertices. (C) 2011 Elsevier B.V. All rights reserved. C1 [Hecht, Frederic; Kuate, Raphael] Univ Paris 06, Lab Jacques Louis Lions, F-75252 Paris 05, France. [Tautges, Timothy] Argone Natl Labs, Div Math & Comp Sci, Madison, WI 53706 USA. RP Kuate, R (reprint author), Univ Paris 06, Lab Jacques Louis Lions, Boite Courrier 187, F-75252 Paris 05, France. EM hecht@ann.jussieu.fr; kuate@ann.jussieu.fr; tautges@mcs.anl.gov NR 9 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0925-7721 J9 COMP GEOM-THEOR APPL JI Comput. Geom.-Theory Appl. PD JAN-FEB PY 2012 VL 45 IS 1-2 BP 62 EP 71 DI 10.1016/j.comgeo.2011.07.002 PG 10 WC Mathematics, Applied; Mathematics SC Mathematics GA 847AY UT WOS:000296945500006 ER PT J AU Wang, W Shu, CW Yee, HC Sjogreen, B AF Wang, Wei Shu, Chi-Wang Yee, H. C. Sjoegreen, Bjoern TI High order finite difference methods with subcell resolution for advection equations with stiff source terms SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE Stiff reaction term; Shock capturing; Detonation; WENO; ENO subcell resolution ID HYPERBOLIC CONSERVATION-LAWS; RANDOM PROJECTION METHOD; REACTION-CONVECTION EQUATIONS; STATE NUMERICAL-SOLUTIONS; SHOCK-CAPTURING SCHEMES; NONLINEAR SOURCE TERMS; EFFICIENT IMPLEMENTATION; DIMENSIONAL DETONATIONS; DYNAMICAL-APPROACH; WAVE-PROPAGATION AB A new high order finite-difference method utilizing the idea of Harten ENO subcell resolution method is proposed for chemical reactive flows and combustion. In reaction problems, when the reaction time scale is very small, e.g., orders of magnitude smaller than the fluid dynamics time scales, the governing equations will become very stiff. Wrong propagation speed of discontinuity may occur due to the underresolved numerical solution in both space and time. The present proposed method is a modified fractional step method which solves the convection step and reaction step separately. In the convection step, any high order shock-capturing method can be used. In the reaction step, an ODE solver is applied but with the computed flow variables in the shock region modified by the Harten subcell resolution idea. For numerical experiments, a fifth-order finite-difference WENO scheme and its anti-diffusion WENO variant are considered. A wide range of 1D and 2D scalar and Euler system test cases are investigated. Studies indicate that for the considered test cases, the new method maintains high order accuracy in space for smooth flows, and for stiff source terms with discontinuities, it can capture the correct propagation speed of discontinuities in very coarse meshes with reasonable CFL numbers. (C) 2011 Elsevier Inc. All rights reserved. C1 [Wang, Wei] Florida Int Univ, Dept Math & Stat, Miami, FL 33199 USA. [Shu, Chi-Wang] Brown Univ, Div Appl Math, Providence, RI 02912 USA. [Yee, H. C.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. [Sjoegreen, Bjoern] Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. RP Wang, W (reprint author), Florida Int Univ, Dept Math & Stat, Miami, FL 33199 USA. EM weiwang1@fiu.edu RI Shu, Chi-Wang/A-3216-2013 OI Shu, Chi-Wang/0000-0001-7720-9564 FU DOE/SciDAC SAP [DE-AI02-06ER25796]; US Department of Energy at Lawrence Livermore National Laboratory [DE-AC52-07NA27344]; ARO [W911NF-08-1-0520]; NASA FX The authors acknowledge the support of the DOE/SciDAC SAP Grant DE-AI02-06ER25796. The work by Bjorn Sjogreen was performed under the auspices of the US Department of Energy at Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The research of C.-W. Shu is also partially supported by ARO Grant W911NF-08-1-0520. The research of H.C. Yee is also partially supported by the NASA Fundamental Aeronautics Hypersonic program. NR 34 TC 19 Z9 21 U1 1 U2 15 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 EI 1090-2716 J9 J COMPUT PHYS JI J. Comput. Phys. PD JAN 1 PY 2012 VL 231 IS 1 BP 190 EP 214 DI 10.1016/j.jcp.2011.08.031 PG 25 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 846ZN UT WOS:000296941800012 ER PT J AU Reilly, A Nozick, L Xu, NX Jones, D AF Reilly, Allison Nozick, Linda Xu, Ningxiong Jones, Dean TI Came theory-based identification of facility use restrictions for the movement of hazardous materials under terrorist threat SO TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW LA English DT Article DE Hazardous materials; Routing; Game theory ID GAME-THEORY; MATERIALS TRANSPORTATION; RISK; NETWORKS; RELIABILITY; SECURITY AB Government agencies can determine which specific facilities in a transportation network to restrict for each class of material and for which times of the day and/or week to stem the consequences of a terrorist event. To guide in making these determinations, this paper develops a three-player game of the interactions among a government agency, a carrier, and a terrorist. It also develops an effective solution procedure for this game and illustrates the use of that procedure on a realistic case study based on the freight rail network in the continental United States. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Reilly, Allison; Nozick, Linda; Xu, Ningxiong] Cornell Univ, Sch Civil & Environm Engn, Ithaca, NY 14853 USA. [Jones, Dean] Sandia Natl Labs, Albuquerque, NM 87185 USA. RP Nozick, L (reprint author), Cornell Univ, Sch Civil & Environm Engn, Hollister Hall, Ithaca, NY 14853 USA. EM Acr39@cornell.edu; lkn3@cornell.edu; nx22@cornell.edu; dajones@sandia.gov NR 35 TC 6 Z9 6 U1 2 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1366-5545 J9 TRANSPORT RES E-LOG JI Transp. Res. Pt. e-Logist. Transp. Rev. PD JAN PY 2012 VL 48 IS 1 SI SI BP 115 EP 131 DI 10.1016/j.tre.2011.06.002 PG 17 WC Economics; Engineering, Civil; Operations Research & Management Science; Transportation; Transportation Science & Technology SC Business & Economics; Engineering; Operations Research & Management Science; Transportation GA 847SY UT WOS:000296994000009 ER PT J AU Regmi, M Chisholm, MF Eres, G AF Regmi, Murari Chisholm, Matthew F. Eres, Gyula TI The effect of growth parameters on the intrinsic properties of large-area single layer graphene grown by chemical vapor deposition on Cu SO CARBON LA English DT Article ID RAMAN-SPECTROSCOPY; EPITAXIAL GRAPHENE; FILMS; GRAPHITE; SIZE AB We present a comprehensive study of the parameter space for single layer graphene growth by chemical vapor deposition on Cu. The temperature is the most widely recognized control parameter in single layer graphene growth. We show that the methane-to-hydrogen ratio and the growth pressure also are critical parameters that affect the structural perfection and the cleanliness of graphene. The optimal conditions for suppressing double and multilayer graphene growth occur near 1000 degrees C, 1:20 methane-to-hydrogen ratio, and a total pressure in the range from 0.5 to 1 Torr. Raman mapping of a 40 x 30 mu m(2) area shows single layer domains with 5-10 mu m linear dimensions. Atomic resolution imaging of suspended graphene by aberration corrected scanning transmission electron microscopy shows that the single layer graphene consists of areas of 10-15 nm linear dimensions and smaller patches of residual contamination that was undetected by other characterization methods. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Regmi, Murari; Chisholm, Matthew F.; Eres, Gyula] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA. RP Eres, G (reprint author), Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA. EM eresg@ornl.gov RI Eres, Gyula/C-4656-2017 OI Eres, Gyula/0000-0003-2690-5214 FU Materials Sciences and Engineering Division, Basic Energy Sciences (BES), U.S. Department of Energy (DOE) FX Research (MFC and GE) sponsored by Materials Sciences and Engineering Division, Basic Energy Sciences (BES), U.S. Department of Energy (DOE), and the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. NR 31 TC 41 Z9 42 U1 7 U2 84 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PD JAN PY 2012 VL 50 IS 1 BP 134 EP 141 DI 10.1016/j.carbon.2011.07.063 PG 8 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 841XP UT WOS:000296548800014 ER PT J AU Cretu, O Rodriguez-Manzo, JA Demortiere, A Banhart, F AF Cretu, O. Rodriguez-Manzo, J. A. Demortiere, A. Banhart, F. TI Electron beam-induced formation and displacement of metal clusters on graphene, carbon nanotubes and amorphous carbon SO CARBON LA English DT Article AB Nanocrystals of different metals with sizes of 2-6 nm are deposited on graphene, carbon nanotubes, or amorphous carbon films. Irradiation with a highly focused electron beam is used to split clusters of a few metal atoms (<1 nm in diameter) from the crystals. The metal clusters follow the electron beam spot on the graphitic surface when the beam is slowly deflected away from the clusters. This unusual behaviour of metals on graphitic surfaces is explained in terms of electron beam-induced activation of the graphitic surfaces and covalent bonding between metal and carbon atoms. The technique might be applicable in (sub-)nanometre structuring of graphene with metal dots. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Cretu, O.; Rodriguez-Manzo, J. A.; Banhart, F.] Univ Strasbourg, CNRS, Inst Phys & Chim Mat, UMR 7504, F-67034 Strasbourg, France. [Demortiere, A.] Argonne Natl Lab, Ctr Nanoscale Mat, Argonne, IL 60439 USA. RP Banhart, F (reprint author), Univ Strasbourg, CNRS, Inst Phys & Chim Mat, UMR 7504, 23 Rue Loess, F-67034 Strasbourg, France. EM florian.banhart@ipcms.unistra.fr RI Banhart, Florian/I-1118-2016; Cretu, Ovidiu/N-3437-2016 OI Cretu, Ovidiu/0000-0002-1822-8172 FU Agence Nationale de la Recherche ANR (NANOCONTACTS) [NT09 507527] FX Funding by the Agence Nationale de la Recherche ANR (NANOCONTACTS, NT09 507527) is gratefully acknowledged. The authors thank M. Acosta, E Scheurer, and G. Schull for supplying specimen material. NR 19 TC 11 Z9 11 U1 2 U2 30 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0008-6223 J9 CARBON JI Carbon PD JAN PY 2012 VL 50 IS 1 BP 259 EP 264 DI 10.1016/j.carbon.2011.08.043 PG 6 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 841XP UT WOS:000296548800029 ER PT J AU Tuncer, E AF Tuncer, Enis TI Layered binary-dielectrics for energy applications: Limitations and potentials SO CURRENT APPLIED PHYSICS LA English DT Article DE Dielectrics; Breakdown; Composite materials; Breakdown strength; Energy storage ID THIN-FILM CAPACITORS; THICKNESS DEPENDENCE; BREAKDOWN AB In this short paper, an attempt is made to illustrate how performance of an electrically insulating material, a dielectric, can be improved by constructing a layered binary-dielectric structure that employs a weak insulator with high dielectric permittivity. It is shown that layered binary-dielectrics could have a significant impact on energy storage and electrical insulation. (C) 2011 Elsevier B. V. All rights reserved. C1 [Tuncer, Enis] Oak Ridge Natl Lab, Div Fus Energy, Appl Superconduct Grp, Oak Ridge, TN 37831 USA. RP Tuncer, E (reprint author), GE Global Res Ctr, Dielect & Electrophys Lab, Niskayuna, NY 12309 USA. EM enis.tuncer@physics.org OI Tuncer, Enis/0000-0002-9324-4324 FU UT-Battelle, LLC [DE-AC05-00OR22725]; U.S. Department of Energy - Office of Electricity Delivery and Energy Reliability, Advanced Cables and Conductors FX This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy - Office of Electricity Delivery and Energy Reliability, Advanced Cables and Conductors Program. The publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. NR 20 TC 0 Z9 0 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1567-1739 J9 CURR APPL PHYS JI Curr. Appl. Phys. PD JAN PY 2012 VL 12 IS 1 BP 337 EP 340 DI 10.1016/j.cap.2011.07.028 PG 4 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA 841PV UT WOS:000296525700062 ER PT J AU Melnichenko, YB He, LL Sakurovs, R Kholodenko, AL Blach, T Mastalerz, M Radlinski, AP Cheng, G Mildner, DFR AF Melnichenko, Yuri B. He, Lilin Sakurovs, Richard Kholodenko, Arkady L. Blach, Tomasz Mastalerz, Maria Radlinski, Andrzej P. Cheng, Gang Mildner, David F. R. TI Accessibility of pores in coal to methane and carbon dioxide SO FUEL LA English DT Article DE Coal; Accessible pores; CO2; Methane; Small-angle neutron scattering ID ANGLE NEUTRON-SCATTERING; BITUMINOUS COAL; AMERICAN COALS; SURFACE-AREA; POROSITY; SORPTION; ADSORPTION; BEHAVIOR; SILICA; USANS AB Fluid-solid interactions in natural and engineered porous solids underlie a variety of technological processes, including geological storage of anthropogenic greenhouse gases, enhanced coal bed methane recovery, membrane separation, and heterogeneous catalysis. The size, distribution and interconnectivity of pores, the chemical and physical properties of the solid and fluid phases collectively dictate how fluid molecules migrate into and through the micro-and meso-porous media, adsorb and ultimately react with the solid surfaces. Due to the high penetration power and relatively short wavelength of neutrons, small-angle neutron scattering (SANS) as well as ultra small-angle scattering (USANS) techniques are ideally suited for assessing the phase behavior of confined fluids under pressure as well as for evaluating the total porosity in engineered and natural porous systems including coal. Here we demonstrate that SANS and USANS can be also used for determining the fraction of the pore volume that is actually accessible to fluids as a function of pore sizes and study the fraction of inaccessible pores as a function of pore size in three coals from the Illinois Basin (USA) and Bowen Basin (Australia). Experiments were performed at CO2 and methane pressures up to 780 bar, including pressures corresponding to zero average contrast condition (ZAC), which is the pressure where no scattering from the accessible pores occurs. Scattering curves at the ZAC were compared with the scattering from same coals under vacuum and analysed using a newly developed approach that shows that the volume fraction of accessible pores in these coals varies between similar to 90% in the macropore region to similar to 30% in the mesopore region and the variation is distinctive for each of the examined coals. The developed methodology may be also applied for assessing the volume of accessible pores in other natural underground formations of interest for CO2 sequestration, such as saline aquifers as well as for estimating closed porosity in engineered porous solids of technological importance. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Melnichenko, Yuri B.; He, Lilin] Oak Ridge Natl Lab, Neutron Scattering Sci Div, Oak Ridge, TN 37831 USA. [Melnichenko, Yuri B.] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA. [Sakurovs, Richard] CSIRO Energy Technol, N Ryde, NSW 2113, Australia. [Kholodenko, Arkady L.] Clemson Univ, HL Hunter Labs 375, Clemson, SC 29634 USA. [Blach, Tomasz; Radlinski, Andrzej P.] Griffith Univ, Nanoscale Sci & Technol Ctr, Brisbane, Qld 4111, Australia. [Mastalerz, Maria; Radlinski, Andrzej P.] Indiana Univ, Indiana Geol Survey, Bloomington, IN 47405 USA. [Cheng, Gang] Sandia Natl Labs, Livermore, CA 94551 USA. [Cheng, Gang] Joint BioEnergy Inst, Emeryville, CA 94608 USA. [Mildner, David F. R.] NIST, Ctr Neutron Res, Gaithersburg, MD 20899 USA. RP Melnichenko, YB (reprint author), Oak Ridge Natl Lab, Neutron Scattering Sci Div, Oak Ridge, TN 37831 USA. EM melnichenkoy@ornl.gov; Richard.Sakurovs@csiro.au OI He, Lilin/0000-0002-9560-8101 FU Laboratory Directed Research and Development Program; Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy; ORNL; Oak Ridge Institute for Science and Education; National Science Foundation [DMR-0454672] FX This research at Oak Ridge National Laboratory's High Flux Isotope Reactor was sponsored by the Laboratory Directed Research and Development Program and the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. This research was supported in part by the ORNL Postdoctoral Research Associates Program, administered jointly by the ORNL and the Oak Ridge Institute for Science and Education. The elements of this work utilizing the BT-5 instrument at the NCNR were supported in part by the National Science Foundation under agreement No. DMR-0454672. Mention of specific commercial products is for informational purposes only and does not constitute endorsement by the National Institute of Standards and Technology. NR 32 TC 27 Z9 30 U1 4 U2 56 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0016-2361 EI 1873-7153 J9 FUEL JI Fuel PD JAN PY 2012 VL 91 IS 1 BP 200 EP 208 DI 10.1016/j.fuel.2011.06.026 PG 9 WC Energy & Fuels; Engineering, Chemical SC Energy & Fuels; Engineering GA 841SD UT WOS:000296532400025 ER PT J AU Mitri, FG Fellah, ZEA AF Mitri, F. G. Fellah, Z. E. A. TI Transverse (lateral) instantaneous force of an acoustical first-order Bessel vortex beam centered on a rigid sphere SO ULTRASONICS LA English DT Article DE Transverse instantaneous force; Bessel vortex (or helicoidal) beam; Rigid movable sphere; Progressive waves ID RADIATION FORCE; ELASTIC SPHERE; SCATTERING AB In a recent report [F.G. Mitri, Z.E.A. Fellah, Ultrasonics 51 (2011) 719-724], it has been found that the instantaneous axial force (i.e. acting along the axis of wave propagation) of a Bessel acoustic beam centered on a sphere is only determined for the fundamental order (i.e. m = 0) but vanishes when the beam is of vortex type (i.e. m > 0, where m is the order (or helicity) of the beam). It has also been recognized that for circularly symmetric beams (such as Bessel beams of integer order), the transverse (lateral) instantaneous force should vanish as required by symmetry. Nevertheless, in this commentary, the present analysis unexpectedly reveals the existence of a transverse instantaneous force on a rigid sphere centered on the axis of a Bessel vortex beam of unit magnitude order (i.e. vertical bar m vertical bar = 1) not reported in [F.G. Mitri, Z.E.A. Fellah, Ultrasonics 51 (2011) 719-724]. The presence of the transverse instantaneous force components of a first-order Bessel vortex beam results from mathematical anti-symmetry in the surface integrals, but vanishes for the fundamental (m = 0) and higher-order Bessel (vortex) beams (i.e. vertical bar m vertical bar > 1). Here, closed-form solutions for the instantaneous force components are obtained and examples for the transverse components for progressive waves are computed for a fixed and a movable rigid sphere. The results show that only the dipole (n = 1) mode in the scattering contributes to the instantaneous force components, as well as how the transverse instantaneous force per unit cross-sectional surface varies versus the dimensionless frequency ka (k is the wave number in the fluid medium and a is the sphere's radius), and the half-cone angle beta of the beam. Moreover, the velocity of the movable sphere is evaluated based on the concept of mechanical impedance. The proposed analysis may be of interest in the analysis of transverse instantaneous forces on spherical particles for particle manipulation and rotation in drug delivery and other biomedical or industrial applications. (C) 2011 Elsevier B.V. All rights reserved. C1 [Mitri, F. G.] Los Alamos Natl Lab, Acoust & Sensors Technol Team, MPA Sensors & Elect Devices 11, Los Alamos, NM 87545 USA. [Fellah, Z. E. A.] CNRS, Lab Mecan & Acoust, UPR 7051, F-13009 Marseille, France. RP Mitri, FG (reprint author), Los Alamos Natl Lab, Acoust & Sensors Technol Team, MPA Sensors & Elect Devices 11, MS D429, Los Alamos, NM 87545 USA. EM mitri@lanl.gov FU Los Alamos National Laboratory [LDRD-X9N9] FX The financial support provided through a Director's fellowship (LDRD-X9N9) from Los Alamos National Laboratory is gratefully acknowledged. Disclosure: this unclassified publication, with the following reference no. LA-UR 11-11236, has been approved for unlimited public release under DUSA ENSCI. NR 13 TC 1 Z9 1 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0041-624X J9 ULTRASONICS JI Ultrasonics PD JAN PY 2012 VL 52 IS 1 BP 151 EP 155 DI 10.1016/j.ultras.2011.07.009 PG 5 WC Acoustics; Radiology, Nuclear Medicine & Medical Imaging SC Acoustics; Radiology, Nuclear Medicine & Medical Imaging GA 841CM UT WOS:000296490100022 PM 21899870 ER PT J AU Tonks, MR Gaston, D Millett, PC Andrs, D Talbot, P AF Tonks, Michael R. Gaston, Derek Millett, Paul C. Andrs, David Talbot, Paul TI An object-oriented finite element framework for multiphysics phase field simulations SO COMPUTATIONAL MATERIALS SCIENCE LA English DT Article DE Phase field model; Finite element method; Jacobian-Free Newton Krylov; Mesh adaptivity ID GRAIN-BOUNDARY MIGRATION; ADAPTIVE MESH REFINEMENT; MICROELASTICITY THEORY; THERMAL-CONDUCTIVITY; COMPUTER-SIMULATION; MODEL; SOLIDIFICATION; MICROSTRUCTURES; TRANSFORMATION; EQUATIONS AB The phase field approach is a powerful and popular method for modeling microstructure evolution. In this work, advanced numerical tools are used to create a framework that facilitates rapid model development. This framework, called MARMOT, is based on Idaho National Laboratory's finite element Multiphysics Object-Oriented Simulation Environment. In MARMOT, the system of phase field partial differential equations (PDEs) are solved simultaneously together with PDEs describing additional physics, such as solid mechanics and heat conduction, using the Jacobian-Free Newton Krylov Method. An object-oriented architecture is created by taking advantage of commonalities in the phase field PDEs to facilitate development of new models with very little effort. In addition, MARMOT provides access to mesh and time step adaptivity, reducing the cost for performing simulations with large disparities in both spatial and temporal scales. In this work, phase separation simulations are used to show the numerical performance of MARMOT. Deformation-induced grain growth and void growth simulations are also included to demonstrate the muliphysics capability. Published by Elsevier B.V. C1 [Tonks, Michael R.; Gaston, Derek; Millett, Paul C.; Andrs, David] Idaho Natl Lab, Idaho Falls, ID 83415 USA. [Talbot, Paul] Oregon State Univ, Corvallis, OR 97331 USA. RP Tonks, MR (reprint author), Idaho Natl Lab, POB 1625, Idaho Falls, ID 83415 USA. EM Michael.Tonks@inl.gov FU Idaho National Laboratory; US Department of Energy [DE-AC07-05ID14517] FX The authors thank Cody Permann from Idaho National Laboratory for his assistance with MOOSE development in support of MARMOT and Bulent Biner from Idaho National Laboratory for his suggestions and advice. We would also like to acknowledge Roy Stogner from the University of Texas for his assistance during the initial stages of this work. This work was funded by an Idaho National Laboratory LDRD project. This manuscript has been authored by Battelle Energy Alliance, LLC under Contract No. DE-AC07-05ID14517 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. NR 24 TC 40 Z9 40 U1 5 U2 57 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-0256 J9 COMP MATER SCI JI Comput. Mater. Sci. PD JAN PY 2012 VL 51 IS 1 BP 20 EP 29 DI 10.1016/j.commatsci.2011.07.028 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA 837OY UT WOS:000296214300004 ER PT J AU Baniassadi, M Mortazavi, B Hamedani, HA Garmestani, H Ahzi, S Fathi-Torbaghan, M Ruch, D Khaleel, M AF Baniassadi, M. Mortazavi, B. Hamedani, H. Amani Garmestani, H. Ahzi, S. Fathi-Torbaghan, M. Ruch, D. Khaleel, M. TI Three-dimensional reconstruction and homogenization of heterogeneous materials using statistical correlation functions and FEM SO COMPUTATIONAL MATERIALS SCIENCE LA English DT Article DE Heterogeneous media; Three-dimensional microstructure reconstruction; Two-point correlation functions; Two-point cluster functions; FEM analysis ID 2-POINT CORRELATION-FUNCTIONS; EFFECTIVE CONDUCTIVITY; RANDOM MICROSTRUCTURES; MULTIPHASE COMPOSITES; 3D RECONSTRUCTION; CONTINUUM THEORY; IMAGE-ANALYSIS; RANDOM-MEDIA; EXPANSIONS; PROPERTY AB In this study, a previously developed reconstruction methodology is extended to three-dimensional reconstruction of a three-phase microstructure, based on two-point correlation functions and two-point cluster functions. The reconstruction process has been implemented based on hybrid stochastic methodology for simulating the virtual microstructure. While different phases of the heterogeneous medium are represented by different cells, growth of these cells is controlled by optimizing parameters such as rotation, shrinkage, translation, distribution and growth rates of the cells. Based on the reconstructed microstructure, finite element method (FEM) was used to compute the effective elastic modulus and effective thermal conductivity. A statistical approach, based on two-point correlation functions, was also used to directly estimate the effective properties of the developed microstructures. Good agreement between the predicted results from FEM analysis and statistical methods was found confirming the efficiency of the statistical methods for prediction of thermo-mechanical properties of three-phase composites. (C) 2011 Elsevier B.V. All rights reserved. C1 [Baniassadi, M.; Mortazavi, B.; Ahzi, S.] Univ Strasbourg, IMFS, F-67000 Strasbourg, France. [Baniassadi, M.; Mortazavi, B.; Ruch, D.] AMS, Ctr Rech Publ Henri Tudor, L-4221 Esch Sur Alzette, Luxembourg. [Hamedani, H. Amani; Garmestani, H.; Ahzi, S.] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA. [Fathi-Torbaghan, M.] Univ Siegen, Fac Elect & Comp Sci, D-57068 Siegen, Germany. [Khaleel, M.] Pacific NW Natl Lab, Richland, WA 99352 USA. RP Baniassadi, M (reprint author), Univ Strasbourg, IMFS, 2 Rue Boussingault, F-67000 Strasbourg, France. EM Majid.Baniassadi@imfs.u-strasbg.fr OI khaleel, mohammad/0000-0001-7048-0749 FU Fond National de la Recherche (FNR) of the Grand Duche of Luxembourg; AFR COTCH Project FX The authors would like to acknowledge the financial support from the Fond National de la Recherche (FNR) of the Grand Duche of Luxembourg (AFR Research Assistantship for Majid Baniassadi) and (AFR COTCH Project Grants for Bohayra Mortazavi). NR 31 TC 21 Z9 21 U1 2 U2 30 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-0256 J9 COMP MATER SCI JI Comput. Mater. Sci. PD JAN PY 2012 VL 51 IS 1 BP 372 EP 379 DI 10.1016/j.commatsci.2011.08.001 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA 837OY UT WOS:000296214300046 ER PT J AU Li, DS Tschopp, MA Khaleel, M Sun, X AF Li, D. S. Tschopp, M. A. Khaleel, M. Sun, X. TI Comparison of reconstructed spatial microstructure images using different statistical descriptors SO COMPUTATIONAL MATERIALS SCIENCE LA English DT Article DE Statistical correlation; Two-point correlation function; Microstructure reconstruction; Lineal path function ID RANDOM-MEDIA; STOCHASTIC RECONSTRUCTION; ALGORITHMS AB The objective of this research is to examine the use of statistical descriptors in the microstructure reconstruction process and the associated effect on microstructure properties. In this work, two-point correlation functions and lineal path functions were used to study the efficiency and accuracy of microstructure reconstruction. A polar plot of the two-point correlation functions is used to quantitatively evaluate the agreement with the target microstructure. In general, as more microstructure descriptors are added for the microstructure reconstruction process, the computational time increases and the reconstructed microstructures quantitatively agree better with the target microstructure. However, in some cases, adding lineal path functions did not always result in a better microstructural representation. Last, finite element analysis of thermal loading in the reconstructed microstructures of loaded nuclear waste glass is used to evaluate the property predictions with those of the target microstructure. Identifying which statistical descriptors are best for different microstructures may provide insight into optimizing the microstructure reconstruction process from limited statistical descriptors. Published by Elsevier B.V. C1 [Li, D. S.; Khaleel, M.; Sun, X.] Pacific NW Natl Lab, Fundamental & Computat Sci Directorate, Richland, WA 99352 USA. [Tschopp, M. A.] Mississippi State Univ, Ctr Adv Vehicular Syst, Starkville, MS 39759 USA. RP Li, DS (reprint author), Pacific NW Natl Lab, Fundamental & Computat Sci Directorate, Richland, WA 99352 USA. EM dongsheng.li@pnl.gov RI Tschopp, Mark/B-1594-2008; OI Tschopp, Mark/0000-0001-8471-5035; khaleel, mohammad/0000-0001-7048-0749 FU US Department of Energy at Pacific Northwest National Laboratory; PNNL LDRD Chemical Imaging Initiative; US Department of Energy [DE-AC05-76RL01830] FX This work was funded by the US Department of Energy's Nuclear Energy Advanced Modeling and Simulation (NEAMS) program at Pacific Northwest National Laboratory. Microstructure reconstruction part is also partially funded by PNNL LDRD Chemical Imaging Initiative project. PNNL is operated by Battelle Memorial Institute for the US Department of Energy under Contract No. DE-AC05-76RL01830. NR 21 TC 13 Z9 13 U1 0 U2 11 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-0256 J9 COMP MATER SCI JI Comput. Mater. Sci. PD JAN PY 2012 VL 51 IS 1 BP 437 EP 444 DI 10.1016/j.commatsci.2011.07.056 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA 837OY UT WOS:000296214300055 ER PT J AU Srinivasan, RS Braham, WW Campbell, DE Curcija, CD AF Srinivasan, Ravi S. Braham, William W. Campbell, Daniel E. Curcija, Charlie D. TI Re(De)fining Net Zero Energy: Renewable Emergy Balance in environmental building design SO BUILDING AND ENVIRONMENT LA English DT Article DE Net Zero Energy; Emergy analysis; Renewable Substitutability; Renewable Emergy Balance; Environmental building design AB The notion that raw materials for building construction are plentiful and can be extracted "at will" from Earth's geobiosphere, and that these materials do not undergo any degradation or related deterioration in performance while in use is alarming and entirely inaccurate. For these reasons, a particular building, like an organism or an ecosystem, must seek self-sustenance for that design to prevail in competition with other building designs in a time with limited availability of energy and materials. To this extent, Net Zero Energy (NZE) buildings achieve a net annual energy balance in their operations. However, approaching an NZE building goal based on current definitions is flawed for two principal reasons (1) NZE only deals with the energy required for operations and related emissions (2) it does not establish a threshold which ensures that buildings are optimized for reduced consumption before renewable systems are integrated to obtain an energy balance. This paper develops a method to maximize renewable resource use through emergy (spelled with an "m") analysis to close the gap between current approaches to environmental building design and the over-arching goal of creating buildings that contribute to a sustainable relationship between human activities and the geobiosphere. This paper proposes using a "Renewable Emergy Balance" (REB) in environmental building design as a tool to maximize renewable resource use through disinvestment of all non-renewable resources that may be substituted with renewable resources. REB buildings attain a high standing by optimizing building construction over their entire life-span from formation-extraction-manufacturing to maintenance and operation. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Srinivasan, Ravi S.] Univ Florida, ME Rinker Sr Sch Bldg Construct, Coll Design Construct & Planning, Gainesville, FL 32611 USA. [Srinivasan, Ravi S.; Braham, William W.] Univ Penn, Sch Design, Dept Architecture, Philadelphia, PA 19104 USA. [Campbell, Daniel E.] US EPA, Off Res & Dev, Natl Hlth & Environm Effects Res Lab, Atlantic Ecol Div, Narragansett, RI 02882 USA. [Curcija, Charlie D.] Univ Calif Berkeley, Lawrence Berkeley Lab, Windows & Daylighting Grp, Berkeley, CA 94720 USA. RP Srinivasan, RS (reprint author), Univ Florida, ME Rinker Sr Sch Bldg Construct, Coll Design Construct & Planning, Gainesville, FL 32611 USA. EM sravi@ufl.edu RI Srinivasan, Ravi/F-1202-2014 OI Srinivasan, Ravi/0000-0002-0461-5729 NR 26 TC 31 Z9 33 U1 3 U2 18 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0360-1323 J9 BUILD ENVIRON JI Build. Environ. PD JAN PY 2012 VL 47 BP 300 EP 315 DI 10.1016/j.buildenv.2011.07.010 PG 16 WC Construction & Building Technology; Engineering, Environmental; Engineering, Civil SC Construction & Building Technology; Engineering GA 830MW UT WOS:000295662100031 ER PT J AU Sidheswaran, MA Destaillats, H Sullivan, DP Cohn, S Fisk, WJ AF Sidheswaran, Meera A. Destaillats, Hugo Sullivan, Douglas P. Cohn, Sebastian Fisk, William J. TI Energy efficient indoor VOC air cleaning with activated carbon fiber (ACF) filters SO BUILDING AND ENVIRONMENT LA English DT Article DE Activated carbon fiber; Volatile organic compound; Indoor pollutant; Energy efficient ventilation ID VOLATILE ORGANIC-COMPOUNDS; PHASE ADSORPTION; CLOTH; REGENERATION; VAPOR AB This study explores the potential environmental and energy benefits of using activated carbon fiber (ACF) filters for air cleaning in HVAC systems. The parallel aims for the air cleaning system were to enable reduced indoor exposures to volatile organic compounds (VOCs) and to simultaneously allow reduced rates and energy consumption for outdoor air ventilation. We evaluated the use of ACF media to adsorb VOCs from indoor air during repeated simulated 12-h to 24-h periods of occupancy. In a cyclic regeneration process. VOCs were desorbed from the ACF media and vented outdoors to enable the next cycle of air cleaning. The VOC removal efficiency of the ACF media was measured using a 9.5-cm(2) ACF specimen exposed to a mixture of VOCs that included toluene, benzene, o-xylene, 1-butanol, limonene, undecane and formaldehyde at 29 degrees C and 30% relative humidity. The concentrations of these model pollutants upstream of the ACF media were in the range 20-30 ppb, to simulate realistic conditions. Velocities through the ACF media were typical of those in normal particle filter systems (similar to 0.5 m s(-1)). Initial tests were conducted to develop a modified multi-component Freundlich isotherm and estimate the maximum adsorption capacity of the media, which was determined to be 90 mg VOC per gram of ACF. Three different ACF regeneration methods were explored using relatively cleaner outdoor air under ambient conditions, with this air humidified, and with the filter heated. It was found that heating the ACF media to similar to 150 degrees C by circulation of a DC current through the fibers for a short period (15 min) yielded the best VOC removal results, allowing for subsequent consistent removal efficiencies of 70-80% for most VOCs. Regeneration with unheated outdoor air was also effective and used less energy (subsequent removal efficiency was 50-60% for most VOCs). ACF did not perform as well in eliminating formaldehyde, for which a maximum removal of 25-30% was achieved with heated regeneration. A mass balance model indicated that the combination of ACF air cleaning and a 50% reduction in ventilation will decrease indoor concentrations of VOCs by 60%-80% and reduce formaldehyde concentrations by 12%-40%. Energy modeling indicated the potential to reduce the energy required for heating and cooling of ventilation air by 35% to almost 50%. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Sidheswaran, Meera A.; Destaillats, Hugo; Sullivan, Douglas P.; Cohn, Sebastian; Fisk, William J.] Lawrence Berkeley Natl Lab, Indoor Environm Dept, Berkeley, CA 94720 USA. [Destaillats, Hugo] Arizona State Univ, Sch Sustainable Engn & Built Environm, Tempe, AZ 85287 USA. RP Destaillats, H (reprint author), Lawrence Berkeley Natl Lab, Indoor Environm Dept, Berkeley, CA 94720 USA. EM HDestaillats@lbl.gov RI Destaillats, Hugo/B-7936-2013 FU U.S. Department of Energy [DE-AC02-05CH11231] FX This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Building Technologies Program of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The authors thank Jerome Lam, Colin McCormick and Joe Hagerman of DOE for program management, R. Maddalena, M. Sleiman, M. Russell, T. Hotchi, and A. Montalbano for technical assistance, and L. Gundel and M. Apte for reviewing a report on which this paper is based. NR 23 TC 34 Z9 37 U1 15 U2 107 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0360-1323 J9 BUILD ENVIRON JI Build. Environ. PD JAN PY 2012 VL 47 BP 357 EP 367 DI 10.1016/j.buildenv.2011.07.002 PG 11 WC Construction & Building Technology; Engineering, Environmental; Engineering, Civil SC Construction & Building Technology; Engineering GA 830MW UT WOS:000295662100037 ER PT J AU Fisk, WJ Black, D Brunner, G AF Fisk, William J. Black, Douglas Brunner, Gregory TI Changing ventilation rates in US offices: Implications for health, work performance, energy, and associated economics SO BUILDING AND ENVIRONMENT LA English DT Article DE Cost-benefit analysis; Economizer; Health; Office; Ventilation rate; Work performance ID INDOOR ENVIRONMENTS; CO2 CONCENTRATIONS; SYMPTOMS AB This paper provides quantitative estimates of benefits and costs of providing different amounts of outdoor air ventilation in U.S. offices. For four scenarios that modify ventilation rates, we estimated changes in sick building syndrome (SBS) symptoms, work performance, short-term absence, and building energy consumption. The estimated annual economic benefits were $13 billion from increasing minimum ventilation rates (VRs) from 8 to 10 Lis per person, $38 billion from increasing minimum VRs from 8 to 15 L/s per person, and $33 billion from increasing VRs by adding outdoor air economizers for the 50% of the office floor area that currently lacks economizers. The estimated $0.04 billion in annual energy-related benefits of decreasing minimum VRs from 8 to 6.5 L/s per person are very small compared to the projected annual costs of $12 billion. Benefits of increasing minimum VRs far exceeded energy costs while adding economizers yielded health, performance, and absence benefits with energy savings. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Fisk, William J.; Black, Douglas] Univ Calif Berkeley, Lawrence Berkeley Lab, Indoor Environm Dept, Berkeley, CA 94720 USA. [Brunner, Gregory] US EPA, Indoor Environm Div, Washington, DC 20460 USA. RP Fisk, WJ (reprint author), Univ Calif Berkeley, Lawrence Berkeley Lab, Indoor Environm Dept, 1 Cyclotron Rd,90R3058, Berkeley, CA 94720 USA. EM wjfisk@lbl.gov FU Indoor Environments Division, Office of Radiation and Indoor Air of the U.S. Environmental Protection Agency (EPA) [DW-89-92224401]; U. S. Department of Energy [DW-89-92224401, DE-AC02-05CH11231] FX This study was funded through interagency agreement DW-89-92224401 between the Indoor Environments Division, Office of Radiation and Indoor Air of the U.S. Environmental Protection Agency (EPA) and the U. S. Department of Energy under contract DE-AC02-05CH11231, to develop an IAQ Scientific Findings Resource Bank (see www.iaqscience.lbl.gov). Conclusions in this paper are those of the authors and not necessarily those of the U.S. EPA. The authors thank Spencer Dutton and Rengie Chan for reviewing a draft of a document on which this paper was based, Woody Delp for analyses of economizer installation in the existing building stock, and Michael Spears for checking calculations. NR 20 TC 20 Z9 20 U1 1 U2 23 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0360-1323 J9 BUILD ENVIRON JI Build. Environ. PD JAN PY 2012 VL 47 BP 368 EP 372 DI 10.1016/j.buildenv.2011.07.001 PG 5 WC Construction & Building Technology; Engineering, Environmental; Engineering, Civil SC Construction & Building Technology; Engineering GA 830MW UT WOS:000295662100038 ER PT J AU Cheng, MD Miller, W New, J Berdahl, P AF Cheng, Meng-Dawn Miller, William New, Joshua Berdahl, Paul TI Understanding the long-term effects of environmental exposure on roof reflectance in California SO CONSTRUCTION AND BUILDING MATERIALS LA English DT Article DE Absorption; Aerosol; Building envelop; Cool-pigmented roof; Principal component analysis; Reflectance; Soot ID AEROSOLS; ABSORPTION AB Contaminants from cool-pigmented roof samples exposed at seven California sites were analyzed for elements and carbons to identify those that degrade or enhance solar reflectance. The losses in solar reflectance varied by site and the color of the sample. The least reflectance drop was observed in the alpine climate, while the largest drop occurred in sites near urban development. The change of reflectance appears cyclical with the onset of seasons having more rainfall. A deposition model suggests that chromium ranks first, iron second, and elemental carbon third in importance to soil light absorption. (C) 2011 Elsevier Ltd. All rights reserved. C1 [Cheng, Meng-Dawn; Miller, William; New, Joshua] Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA. [Berdahl, Paul] Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Cheng, MD (reprint author), Oak Ridge Natl Lab, POB 2008,MS 6038, Oak Ridge, TN 37831 USA. EM chengmd@ornl.gov RI Cheng, Meng-Dawn/C-1098-2012; OI Cheng, Meng-Dawn/0000-0003-1407-9576 FU California Energy Commission through the US Department of Energy [DE-AC03-76SF00098]; U.S. Dept. of Energy [DE-AC05-00OR22725] FX Funding for this project was provided by the California Energy Commission's Public Interest Energy Research program through the US Department of Energy under contract DE-AC03-76SF00098. The elemental composition of particles was analyzed by the analytical chemistry services at the DOE Y12 complex using ICP-AES instrument. Oak Ridge National Laboratory is managed by UT-Battelle. LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. NR 21 TC 11 Z9 11 U1 0 U2 6 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0950-0618 EI 1879-0526 J9 CONSTR BUILD MATER JI Constr. Build. Mater. PD JAN PY 2012 VL 26 IS 1 BP 516 EP 526 DI 10.1016/j.conbuildmat.2011.06.052 PG 11 WC Construction & Building Technology; Engineering, Civil; Materials Science, Multidisciplinary SC Construction & Building Technology; Engineering; Materials Science GA 831TO UT WOS:000295754200061 ER PT J AU Gallard, J Lebre, A Morin, C Naughton, T Scott, SL Vallee, G AF Gallard, Jerome Lebre, Adrien Morin, Christine Naughton, Thomas Scott, Stephen L. Vallee, Geoffroy TI Architecture for the next generation system management tools SO FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE LA English DT Article; Proceedings Paper CT International Conference on Utility and Cloud Computing CY DEC, 2010 CL Chennai, INDIA DE HPC system resource management; Flexibility; Virtualization; Emulation; Distributed systems; Virtual platform (VP); Virtual system environment (VSE) ID CLOUDS AB To get more results or greater accuracy, computational scientists execute their applications on distributed computing platforms such as clusters, grids, and clouds. These platforms are different in terms of hardware and software resources as well as locality: some span across multiple sites and multiple administrative domains, whereas others are limited to a single site/domain. As a consequence, in order to scale their applications up, the scientists have to manage technical details for each target platform. From our point of view, this complexity should be hidden from the scientists, who, in most cases, would prefer to focus on their research rather than spending time dealing with platform configuration concerns. In this article, we advocate for a system management framework that aims to automatically set up the whole run-time environment according to the applications' needs. The main difference with regards to usual approaches is that they generally only focus on the software layer whereas we address both the hardware and the software expectations through a unique system. For each application, scientists describe their requirements through the definition of a virtual platform (VP) and a virtual system environment (VSE). Relying on the VP/VSE definitions, the framework is in charge of (i) the configuration of the physical infrastructure to satisfy the VP requirements, (ii) the set-up of the VP, and (iii) the customization of the execution environment (VSE) upon the former VP. We propose a new formalism that the system can rely upon to successfully perform each of these three steps without burdening the user with the specifics of the configuration for the physical resources, and system management tools. This formalism leverages Goldberg's theory for recursive virtual machines (Goldberg, 1973 [6]) by introducing new concepts based on system virtualization (identity, partitioning, aggregation) and emulation (simple, abstraction). This enables the definition of complex VP/VSE configurations without making assumptions about the hardware and the software resources. For each requirement, the system executes the corresponding operation with the appropriate management tool. As a proof of concept, we implemented a first prototype that currently interacts with several system management tools (e.g., OSCAR, the Grid'5000 toolkit, and XtreemOS) and that can be easily extended to integrate new resource brokers or cloud systems such as Nimbus, OpenNebula, or Eucalyptus, for instance. (C) 2011 Elsevier B.V. All rights reserved. C1 [Gallard, Jerome; Morin, Christine] INRIA Rennes, Bretagne Atlantique, France. [Naughton, Thomas; Scott, Stephen L.; Vallee, Geoffroy] Oak Ridge Natl Lab, Oak Ridge, TN 37830 USA. [Lebre, Adrien] Ecole Mines Nantes, Nantes, France. RP Gallard, J (reprint author), INRIA Rennes, Bretagne Atlantique, France. EM Jerome.Gallard@inria.ir; adrien.lebre@emn.fr; Christine.Morin@inria.fr; naughtont@ornl.gov; scottsl@ornl.gov; valleegr@ornl.gov NR 35 TC 1 Z9 1 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-739X EI 1872-7115 J9 FUTURE GENER COMP SY JI Futur. Gener. Comp. Syst. PD JAN PY 2012 VL 28 IS 1 BP 136 EP 146 DI 10.1016/j.future.2011.06.003 PG 11 WC Computer Science, Theory & Methods SC Computer Science GA 834GN UT WOS:000295947900016 ER PT J AU Bradonjic, M Lazos, L AF Bradonjic, Milan Lazos, Loukas TI Graph-based criteria for spectrum-aware clustering in cognitive radio networks SO AD HOC NETWORKS LA English DT Article DE Cognitive radio networks; Clustering; Graph theory; Biclique graphs; Bipartite graphs; Opportunistic access; Open spectrum ID AD-HOC NETWORKS; WIRELESS NETWORKS; SENSOR NETWORKS; CONNECTIVITY; BIPARTITE; CLIQUE; ACCESS AB Cognitive radios (CRS) can exploit vacancies in licensed frequency bands to self-organize in opportunistic spectrum networks. Such networks, henceforth referred to as cognitive radio networks (CRNs), operate over a dynamic bandwidth in both time and space. This inherently leads to the partition of the network into clusters depending on the spatial variation of the primary radio network (PRN) activity. In this article, we analytically evaluate the performance of a new class of clustering criteria designed for CRNs, which explicitly take into account the spatial variations of spectrum opportunities. We jointly represent the network topology and spectrum availability using bipartite graphs. This representation reduces the problem of spectrum-aware cluster formation to a biclique construction problem. We investigate several criteria for constructing clusters for the CRN environment, and characterize their performance under different spectrum sensing and PR activity models. In particular, we evaluate the expected cluster size and number of common idle channels within each cluster, as a function of the spectrum and topology variability. We verify our analytical results via extensive simulations. (C) 2011 Elsevier B.V. All rights reserved. C1 [Lazos, Loukas] Univ Arizona, Dept Elect & Comp Engn, Tucson, AZ 85721 USA. [Bradonjic, Milan] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA. [Bradonjic, Milan] Los Alamos Natl Lab, Ctr Nonlinear Studies, Los Alamos, NM 87545 USA. RP Lazos, L (reprint author), Univ Arizona, Dept Elect & Comp Engn, 1230 E Speedway Blvd, Tucson, AZ 85721 USA. EM milan@lanl.gov; llazos@ece.arizona.edu FU Department of Energy ASCR; National Science Foundation (NSF) [CNS-0844111, CNS-1016943] FX Milan Bradonjic was supported in part by the Department of Energy ASCR program. Loukas Lazos was supported in part by the National Science Foundation (under NSF Grants CAREER CNS-0844111, CNS-1016943). Any opinions, findings, conclusions, or recommendations expressed in this paper are those of the author(s) and do not necessarily reflect the views of NSF. NR 49 TC 8 Z9 8 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1570-8705 EI 1570-8713 J9 AD HOC NETW JI Ad Hoc Netw. PD JAN PY 2012 VL 10 IS 1 BP 75 EP 94 DI 10.1016/j.adhoc.2011.05.009 PG 20 WC Computer Science, Information Systems; Telecommunications SC Computer Science; Telecommunications GA 831VF UT WOS:000295758500006 ER PT J AU Haines, BM Aranson, IS Berlyand, L Karpeev, DA AF Haines, Brian M. Aranson, Igor S. Berlyand, Leonid Karpeev, Dmitry A. TI EFFECTIVE VISCOSITY OF BACTERIAL SUSPENSIONS: A THREE-DIMENSIONAL PDE MODEL WITH STOCHASTIC TORQUE SO COMMUNICATIONS ON PURE AND APPLIED ANALYSIS LA English DT Article DE Bacterial suspensions; effective viscosity; homogenization ID CONCENTRATED SUSPENSIONS; PARTICLES; MICROORGANISMS; SYSTEMS; STRESS; FLUID; FORCE AB We present a PDE model for dilute suspensions of swimming bacteria in a three-dimensional Stokesian fluid. This model is used to calculate the statistically-stationary bulk deviatoric stress and effective viscosity of the suspension from the microscopic details of the interaction of an elongated body with the background flow. A bacterium is modeled as an impenetrable prolate spheroid with self-propulsion provided by a point force, which appears in the model as an inhomogeneous delta function in the PDE. The bacterium is also subject to a stochastic torque in order to model tumbling (random reorientation). Due to a bacterium's asymmetric shape, interactions with prescribed generic planar background flows, such as a pure straining or planar shear flow, cause the bacterium to preferentially align in certain directions. Due to the stochastic torque, the steady-state distribution of orientations is unique for a given background flow. Under this distribution of orientations, self-propulsion produces a reduction in the effective viscosity. For sufficiently weak background flows, the effect of self-propulsion on the effective viscosity dominates all other contributions, leading to an effective viscosity of the suspension that is lower than the viscosity of the ambient fluid. This is in qualitative agreement with recent experiments on suspensions of Bacillus subtths. C1 [Haines, Brian M.; Berlyand, Leonid] Penn State Univ, Dept Math, University Pk, PA 16802 USA. [Aranson, Igor S.] Argonne Natl Lab, Div Mat Sci, Argonne, IL 60439 USA. [Karpeev, Dmitry A.] Argonne Natl Lab, Div Math & Comp Sci, Argonne, IL 60439 USA. RP Haines, BM (reprint author), Penn State Univ, Dept Math, McAllister Bldg, University Pk, PA 16802 USA. EM haines@math.psu.edu; aronson@anl.gov; berlyand@math.psu.edu; karpeev@mcs.anl.gov RI Aranson, Igor/I-4060-2013 FU US DOE Office of Basic Energy Sciences, Division of Materials Science and Engineering [DE-AC02-06CH11357]; DOE [DE-FG02-08ER25862]; NSF [DMS-0708324] FX The work of I. S. Aranson was supported by the US DOE Office of Basic Energy Sciences, Division of Materials Science and Engineering, contract DE-AC02-06CH11357. The work of B. Haines and L. Berlyand was supported by the DOE grant DE-FG02-08ER25862 and NSF grant DMS-0708324. NR 38 TC 7 Z9 7 U1 0 U2 18 PU AMER INST MATHEMATICAL SCIENCES PI SPRINGFIELD PA PO BOX 2604, SPRINGFIELD, MO 65801-2604 USA SN 1534-0392 J9 COMMUN PUR APPL ANAL JI Commun. Pure Appl. Anal PD JAN PY 2012 VL 11 IS 1 BP 19 EP 46 DI 10.3934/cpaa.2012.11.19 PG 28 WC Mathematics, Applied; Mathematics SC Mathematics GA 824OA UT WOS:000295210000003 ER EF