Dynamics and conformational sampling are essential for linking protein structure to biological function. While challenging to probe experimentally, computer simulations are widely used to describe protein dynamics, but at significant computational costs that continue to limit the systems that can be studied. Here, we demonstrate that machine learning can be trained with simulation data to directly generate physically realistic conformational ensembles of proteins without the need for any sampling and at negligible computational cost. As a proof-of-principle we train a generative adversarial network based on a transformer architecture with self-attention on coarse-grained simulations of intrinsically disordered peptides. The resulting model, idpGAN, can predict sequence-dependent coarse-grained ensembles for sequences that are not present in the training set demonstrating that transferability can be achieved beyond the limited training data. We also retrain idpGAN on atomistic simulation data to show that the approach can be extended in principle to higher-resolution conformational ensemble generation.

VL - 14 SN - 2041-1723 UR - https://doi.org/10.1038/s41467-023-36443-x IS - 1 JO - Nature Communications ER - TY - JOUR T1 - Comparison of Electron Capture Rates in the N = 50 Region using 1D Simulations of Core-collapse Supernovae JF - The Astrophysical Journal Y1 - 2022 A1 - Zac Johnston A1 - Sheldon Wasik A1 - Rachel Titus A1 - MacKenzie L. Warren A1 - Evan P. O’Connor A1 - Remco Zegers A1 - Sean M. Couch AB -Recent studies have highlighted the sensitivity of core-collapse supernovae (CCSNe) models to electron-capture (EC) rates on neutron-rich nuclei near the N = 50 closed-shell region. In this work, we perform a large suite of one-dimensional CCSN simulations for 200 stellar progenitors using recently updated EC rates in this region. For comparison, we repeat the simulations using two previous implementations of EC rates: a microphysical library with parametrized N = 50 rates (LMP), and an older independent-particle approximation (IPA). We follow the simulations through shock revival up to several seconds post-bounce, and show that the EC rates produce a consistent imprint on CCSN properties, often surpassing the role of the progenitor itself. Notable impacts include the timescale of core collapse, the electron fraction and mass of the inner core at bounce, the accretion rate through the shock, the success or failure of revival, and the properties of the central compact remnant. We also compare the observable neutrino signal of the neutronization burst in a DUNE-like detector, and find consistent impacts on the counts and mean energies. Overall, the updated rates result in properties that are intermediate between LMP and IPA, and yet slightly more favorable to explosion than both.

VL - 939 UR - https://dx.doi.org/10.3847/1538-4357/ac9306 ER - TY - JOUR T1 - Numerical Study of High Speed Evaporating Sprays JF - International Journal of Multiphase Flow Y1 - 2015 A1 - Farhad A Jaberi A1 - Irannejad, Abolfazl VL - 70 UR - http://www.sciencedirect.com/science/article/pii/S0301932214002341 ER - TY - Generic T1 - High Fidelity Simulations of Turbulent Spray Combustion T2 - Canadian Society for Mechanical Engineering International Congress Y1 - 2014 A1 - Irannejad, A A1 - Banaeizadeh, A. A1 - Jaberi, F.A. JF - Canadian Society for Mechanical Engineering International Congress ER - TY - JOUR T1 - Large Eddy Simulation of Turbulent Spray Breakup and Evaporation JF - International Journal of Multiphase Flow Y1 - 2014 A1 - Irannejad, A A1 - Jaberi, F.A. VL - 61 UR - http://www.sciencedirect.com/science/article/pii/S030193221400010X ER - TY - JOUR T1 - Numerical Investigations of Shock Wave Interactions with a Supersonic Turbulent Boundary Layer JF - Physics of Fluids Y1 - 2014 A1 - A. Jammalamadaka A1 - Li, Z. A1 - Jaberi, F.A. VL - 26 UR - http://scitation.aip.org/content/aip/journal/pof2/26/5/10.1063/1.4873495 IS - 5 ER - TY - JOUR T1 - Spatially-Explicit Integrated Uncertainty and Sensitivity Analysis of Criteria Weights in Multicriteria Land Suitability Evaluation JF - Environmental Modelling & Software Y1 - 2014 A1 - Ligmann-Zielinskaa, Arika A1 - Jankowskib, Piotr VL - 57 UR - http://www.geo.msu.edu/~stsa/pubs/EMS2014_reprint.pdf ER - TY - JOUR T1 - Two-Phase Filtered Mass Density Function for LES of Turbulent Reacting Flows JF - Journal of Fluid Mechanics Y1 - 2014 A1 - Banaeizadeh, A. A1 - Jaberi, F.A. A1 - Li, Z. VL - 760 UR - http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9402098&fileId=S0022112014005734 ER - TY - JOUR T1 - Accuracy of the new pairing theory and its improvement JF - PHYSICAL REVIEW C Y1 - 2013 A1 - L.Y. Jia VL - 88 UR - http://journals.aps.org/prc/abstract/10.1103/PhysRevC.88.064321 ER - TY - JOUR T1 - CLASH: Three Strongly Lensed Images of a Candidate z 11 Galaxy JF - The Astrophysical Journal Y1 - 2013 A1 - Coe, Dan A1 - Zitrin, Adi A1 - Carrasco, Mauricio A1 - Shu, Xinwen A1 - Zheng, Wei A1 - Postman, Marc A1 - Bradley, Larry A1 - Koekemoer, Anton A1 - Bouwens, Rychard A1 - Broadhurst, Tom A1 - Monna, Anna A1 - Host, Ole A1 - Moustakas, Leonidas A A1 - Ford, Holland A1 - Moustakas, John A1 - van der Wel, Arjen A1 - Donahue, Megan A1 - Rodney, Steven A A1 - Ben{\'ıtez, Narciso A1 - Jouvel, Stephanie A1 - Seitz, Stella A1 - Kelson, Daniel D. A1 - Rosati, Piero KW - clusters KW - distances and redshifts KW - early universe KW - galaxies KW - individual VL - 762 ER - TY - JOUR T1 - CLASH: Three Strongly Lensed Images of a Candidate z~11 Galaxy JF - The Astrophysical Journal Y1 - 2013 A1 - Coe, Dan A1 - Zitrin, Adi A1 - Carrasco, Mauricio A1 - Shu, Xinwen A1 - Zheng, Wei A1 - Postman, Marc A1 - Bradley, Larry A1 - Koekemoer, Anton A1 - Bouwens, Rychard A1 - Broadhurst, Tom A1 - Monna, Anna A1 - Host, Ole A1 - Moustakas, Leonidas A A1 - Ford, Holland A1 - Moustakas, John A1 - van der Wel, Arjen A1 - Donahue, Megan A1 - Rodney, Steven A A1 - Benítez, Narciso A1 - Jouvel, Stephanie A1 - Seitz, Stella A1 - Kelson, Daniel D. A1 - Rosati, Piero KW - clusters KW - distances and redshifts KW - early universe KW - galaxies KW - individual VL - 762 IS - 1 ER - TY - ABST T1 - Large Eddy Simulation of Evaporating Spray with a Stochastic Breakup Model Y1 - 2013 A1 - Irannejad, Abolfazl A1 - Jaberi, Farhad AB -Large Eddy Simulations of atomization and evaporation of liquid fuel sprays in diesel engine conditions are performed with stochastic breakup and non-equilibrium droplet heat and mass transfer models. The size and number density of the droplets generated by the breakup model are assumed to be governed by a Fokker-Planck equation, describing the evolution of the {PDF} of droplet radii. The fragmentation intensity spectrum is considered to be Gaussian and the scale of Lagrangian relative velocity fluctuations is included in the breakup frequency calculations. The aerodynamic interactions of droplets in the dense part of the spray are modeled by correcting the relative velocity of droplets in the wake of other droplets. The stochastic breakup model is employed together with the wake interaction model for simulations of non-evaporating and evaporating sprays in various gas temperature and pressure conditions. The predicted results for physical spray parameters, such as the spray penetration length are found to be in good agreement with the available experimental data.

PB - {SAE} International CY - Warrendale, {PA} UR - http://papers.sae.org/2013-01-1101/ ER - TY - Generic T1 - Large Eddy Simulation of Spray Mixing and Combustion with Two-Phase Filtered Mass Density Function T2 - 43rd AIAA Fluid Dynamics Conference Y1 - 2013 A1 - Irannejad, A A1 - Jaberi, F. JF - 43rd AIAA Fluid Dynamics Conference CY - San Diego, California ER - TY - JOUR T1 - Large-Eddy Simulations of Turbulent Flows in Internal Combustion Engines, International Journal of Heat and Mass Transfer Y1 - 2013 A1 - Banaeizadeh, A. A1 - Afshari, A. A1 - H. Schock A1 - Jaberi, F. VL - Vol. 60 IS - No. 10 ER - TY - ABST T1 - Numerical Simulations of Turbulent Sprays with a Multicomponent Evaporation Model Y1 - 2013 A1 - S. Srivastava A1 - H. Schock A1 - Jaberi, F. AB -A multicomponent droplet evaporation model which discretizes the one-dimensional mass and temperature profiles inside a droplet with a finite volume method has been developed and implemented into a large-eddy simulation ({LES)} model for spray simulations. The {LES} and multicomponent models were used along with the {KH-RT} secondary droplet breakup model to simulate realistic fuel sprays in a closed vessel. The effect of various spray and ambient gas parameters on the liquid penetration length of different single component and multicomponent fuels was investigated. The numerical results indicate that the spray penetration length decreases non-linearly with increasing gas temperature or pressure and is less sensitive to changes in ambient gas conditions at higher temperatures or pressures. The spray models and {LES} were found to predict the experimental results for n-hexadecane and two multicomponent surrogate diesel fuels reasonably well.

PB - {SAE} International CY - Warrendale, {PA} UR - http://papers.sae.org/2013-01-1603/ ER - TY - BOOK T1 - Proceedings of the 21st International Meshing Roundtable: An h-r Moving Mesh Method for One-Dimensional Time-Dependent PDEs Y1 - 2013 A1 - Benjamin Ong A1 - Russell, Robert A1 - Ruuth, Steven ED - Jiao, Xiangmin ED - Weill, Jean-Christophe PB - Springer Berlin Heidelberg CY - Berlin, Heidelberg SN - 978-3-642-33573-0 ER - TY - JOUR T1 - Subgrid-Scale Models for Large-Eddy Simulations of Shock-Boundary Layer Interactions, JF - AIAA Journal Y1 - 2013 A1 - A. Jammalamadaka A1 - Li, Z. A1 - Jaberi, F.A. VL - Vol. 5 IS - No. 5 ER - TY - JOUR T1 - A Census of Star-Forming Galaxies in the z~9-10 Universe based on HST+Spitzer Observations Over 19 CLASH clusters: Three Candidate z~9-10 Galaxies and Improved Constraints on the Star Formation Rate Density at z~9.2 JF - Astrophysical Journal Y1 - 2012 A1 - Bouwens, R, A1 - Bradley, L A1 - Zitrin, A. A1 - Coe, D. A1 - Franx, M. A1 - Zheng, W A1 - Smit, R A1 - Host, O. A1 - Postman, M. A1 - Moustakas, L A1 - Labbe, I A1 - Carrasco, M. A1 - Molino, A. A1 - Donahue, M A1 - Kelson, D. D A1 - Meneghetti, M A1 - Jha, S. A1 - Benitez, N A1 - Lemze, D A1 - Umetsu, K A1 - Broadhurst, T. A1 - Moustakas, J. A1 - Rosati, P. A1 - Bartelmann, M A1 - Ford, H A1 - Graves, G. A1 - Grillo, C. A1 - Infante, L A1 - Jiminez-Teja, Y A1 - Jouvel, S A1 - Lahav, O. A1 - Maoz, D A1 - Medezinski, E A1 - Melchior, P A1 - Merten, J A1 - Nonino, M. A1 - Ogaz, S. A1 - Seitz, S. KW - Astrophysics - Cosmology and Extragalactic Astrophysics ER - TY - JOUR T1 - CLASH: Discovery of a Bright z ~= 6.2 Dwarf Galaxy Quadruply Lensed by MACS J0329.6-0211 JF - The Astrophysical Journal Letters Y1 - 2012 A1 - Zitrin, A. A1 - Moustakas, J. A1 - Bradley, L A1 - Coe, D. A1 - Moustakas, L. A. A1 - Postman, M. A1 - Shu, X A1 - Zheng, W A1 - Benítez, N. A1 - Bouwens, R. A1 - Broadhurst, T. A1 - Ford, H A1 - Host, O. A1 - Jouvel, S A1 - Koekemoer, A. A1 - Meneghetti, M A1 - Rosati, P. A1 - Donahue, M A1 - Grillo, C. A1 - Kelson, D. A1 - Lemze, D A1 - Medezinski, E A1 - Molino, A. A1 - Nonino, M. A1 - Ogaz, S. KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J0329.6-0211 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 747 IS - 1 ER - TY - JOUR T1 - CLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis JF - The Astrophysical Journal Y1 - 2012 A1 - Umetsu, Keiichi A1 - Medezinski, Elinor A1 - Nonino, Mario A1 - Merten, Julian A1 - Zitrin, Adi A1 - Molino, Alberto A1 - Grillo, Claudio A1 - Carrasco, Mauricio A1 - Donahue, Megan A1 - Mahdavi, Andisheh A1 - Coe, Dan A1 - Postman, Marc A1 - Koekemoer, Anton A1 - Czakon, Nicole A1 - Sayers, Jack A1 - Mroczkowski, Tony A1 - Golwala, Sunil A1 - Koch, Patrick M A1 - Lin, Kai-Yang A1 - Molnar, Sandor M A1 - Rosati, Piero A1 - Balestra, Italo A1 - Mercurio, Amata A1 - Scodeggio, Marco A1 - Biviano, Andrea A1 - Anguita, Timo A1 - Infante, Leopoldo A1 - Seidel, Gregor A1 - Sendra, Irene A1 - Jouvel, Stephanie A1 - Host, Ole A1 - Lemze, Doron A1 - Broadhurst, Tom A1 - Meneghetti, Massimo A1 - Moustakas, Leonidas A1 - Bartelmann, Matthias A1 - Benítez, Narciso A1 - Bouwens, Rychard A1 - Bradley, Larry A1 - Ford, Holland A1 - Jiménez-Teja, Yolanda A1 - Kelson, Daniel A1 - Lahav, Ofer A1 - Melchior, Peter A1 - Moustakas, John A1 - Ogaz, Sara A1 - Seitz, Stella A1 - Zheng, Wei KW - cosmology: observations KW - dark matter KW - galaxies: clusters: individual: MACS J1206.2-0847 KW - gravitational lensing: strong KW - gravitational lensing: weak VL - 755 IS - 1 ER - TY - JOUR T1 - CLASH: New Multiple Images Constraining the Inner Mass Profile of MACS J1206.2-0847 JF - The Astrophysical Journal Y1 - 2012 A1 - Zitrin, A. A1 - Rosati, P. A1 - Nonino, M. A1 - Grillo, C. A1 - Postman, M. A1 - Coe, D. A1 - Seitz, S. A1 - Eichner, T A1 - Broadhurst, T. A1 - Jouvel, S A1 - Balestra, I. A1 - Mercurio, A A1 - Scodeggio, M A1 - Benítez, N. A1 - Bradley, L A1 - Ford, H A1 - Host, O. A1 - Jimenez-Teja, Y A1 - Koekemoer, A. A1 - Zheng, W A1 - Bartelmann, M A1 - Bouwens, R. A1 - Czoske, O A1 - Donahue, M A1 - Graur, O A1 - Graves, G. A1 - Infante, L A1 - Jha, S. A1 - Kelson, D. A1 - Lahav, O. A1 - Lazkoz, R A1 - Lemze, D A1 - Lombardi, M. A1 - Maoz, D A1 - McCully, C. A1 - Medezinski, E A1 - Melchior, P A1 - Meneghetti, M A1 - Merten, J A1 - Molino, A. A1 - Moustakas, L. A. A1 - Ogaz, S. A1 - Patel, B. A1 - Regoes, E. A1 - Riess, A. A1 - Rodney, S A1 - Umetsu, K A1 - Van der Wel, A. KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J1206.2–0847 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 749 IS - 2 ER - TY - JOUR T1 - CLASH: Precise New Constraints on the Mass Profile Galaxy Cluster A2261 JF - The Astrophysical Journal Y1 - 2012 A1 - Coe, Dan A1 - Umetsu, Keiichi A1 - Zitrin, Adi A1 - Donahue, Megan A1 - Medezinski, Elinor A1 - Postman, Marc A1 - Carrasco, Mauricio A1 - Anguita, Timo A1 - Geller, Margaret J A1 - Rines, Kenneth J. A1 - Diaferio, Antonaldo A1 - Kurtz, Michael J A1 - Bradley, Larry A1 - Koekemoer, Anton A1 - Zheng, Wei A1 - Nonino, Mario A1 - Molino, Alberto A1 - Mahdavi, Andisheh A1 - Lemze, Doron A1 - Infante, Leopoldo A1 - Ogaz, Sara A1 - Melchior, Peter A1 - Host, Ole A1 - Ford, Holland A1 - Grillo, Claudio A1 - Rosati, Piero A1 - Jiménez-Teja, Yolanda A1 - Moustakas, John A1 - Ascaso, Begoña A1 - Lahav, Ofer; A1 - Bartelmann, Matthias A1 - Benítez, Narciso A1 - Bouwens, Rychard A1 - Graur, Or A1 - Graves, Genevieve A1 - Jha, Saurab A1 - Jouvel, Stephanie A1 - Kelson, Daniel A1 - Moustakas, Leonidas A1 - Maoz, Dan A1 - Meneghetti, Massimo A1 - Merten, Julian A1 - Riess, Adam A1 - Rodney, Steve A1 - Seitz, Stella VL - 757 IS - 1 ER - TY - JOUR T1 - Evaluating DEM source and resolution uncertainties in the Soil and Water Assessment Tool JF - Stochastic Environmental Research & Risk Assessment Y1 - 2012 A1 - Lin, Shengpan A1 - C. Jing A1 - N.A. Coles A1 - V. Chaplot A1 - Moore, Nathan A1 - Wu, Jiaping VL - 27 IS - 1 ER - TY - JOUR T1 - A magnified young galaxy from about 500 million years after the Big Bang JF - Nature Y1 - 2012 A1 - Zheng, Wei A1 - Postman, Marc A1 - Zitrin, Adi A1 - Moustakas, John A1 - Shu, Xinwen A1 - Jouvel, Stephanie A1 - Høst, Ole A1 - Molino, Alberto A1 - Bradley, Larry A1 - Coe, Dan A1 - Moustakas, Leonidas A A1 - Carrasco, Mauricio A1 - Ford, Holland A1 - Benítez, Narciso A1 - Lauer, Tod R A1 - Seitz, Stella; B A1 - Bouwens, Rychard A1 - Koekemoer, Anton A1 - Medezinski, Elinor A1 - Bartelmann, Matthias A1 - Broadhurst, Tom A1 - Donahue, Megan A1 - Grillo, Claudio A1 - Infante, Leopoldo A1 - Jha, Saurabh W A1 - Kelson, Daniel D. A1 - Lahav, Ofer A1 - Lemze, Doron A1 - Melchior, Peter A1 - Meneghetti, Massimo A1 - Merten, Julian A1 - Nonino, Mario A1 - Ogaz, Sara A1 - Rosati, Piero A1 - Umetsu, Keiichi A1 - van der Wel, Arjen VL - 489 IS - 7416 ER - TY - JOUR T1 - Mass Measurements of the Neutron-Deficient 41Ti, 45Cr, 49Fe, and 53Ni Nuclides: ￼First Test of the Isobaric Multiplet Mass Equation in fp-Shell Nuclei JF - PHYSICAL REVIEW LETTERS Y1 - 2012 A1 - Y.H. Zhang A1 - H.S. Xu A1 - Yu. A. Litvinov A1 - X.L. Tu A1 - X.L. Yan A1 - S. Typel A1 - K. Blaum A1 - M. Wang A1 - X.H. Zhou A1 - Y. Sun A1 - B. A. Brown A1 - Y.J. Yuan A1 - J.W. Xia A1 - J.C. Yang A1 - G. Audi A1 - X.C. Chen A1 - G.B. Jia A1 - Z.G. Hu A1 - X.W. Ma A1 - R.S. Mao A1 - B. Mei A1 - P. Shuai A1 - Z.Y. Sun A1 - S.T. Wang A1 - G.Q. Xiao A1 - X. Xu A1 - T. Yamaguchi A1 - Y. Yamaguchi A1 - Y.D. Zang A1 - H.W. Zhao A1 - T.C. Zhao A1 - W. Zhang A1 - W.L. Zhan VL - 109 UR - http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.109.102501 ER - TY - CONF T1 - Approximate kernel k-means: solution to large scale kernel clustering T2 - Proceedings of the 17th ACM SIGKDD international conference on Knowledge discovery and data mining Y1 - 2011 A1 - Chitta, Radha A1 - Jin, Rong A1 - Havens, Timothy C. A1 - Jain, Anil K. KW - k-means KW - kernel clustering KW - large-scale clustering JF - Proceedings of the 17th ACM SIGKDD international conference on Knowledge discovery and data mining T3 - KDD '11 PB - ACM CY - San Diego, CA, USA SN - 978-1-4503-0813-7 ER - TY - CONF T1 - Multi-label Learning with Incomplete Class Assignments T2 - Proceedings of IEEE Conference on Computer Vision and Pattern Recognition (CVPR 2011) Y1 - 2011 A1 - S.S. Bucak A1 - Jin, Rong A1 - Jain, Anil K. JF - Proceedings of IEEE Conference on Computer Vision and Pattern Recognition (CVPR 2011) ER - TY - CONF T1 - Speedup of fuzzy and possibilistic c-means for large-scale clustering T2 - IEEE Int. Conf. Fuzzy Systems Y1 - 2011 A1 - Havens, Timothy C. A1 - Chitta, Radha A1 - Jain, Anil K. A1 - Jin, Rong JF - IEEE Int. Conf. Fuzzy Systems CY - Taipei, Taiwan ER - TY - JOUR T1 - A High-Order Finite-Difference Method for Numerical Simulations of Supersonic Turbulent Flows JF - International Journal of Numerical Methods in Fluids Y1 - 2010 A1 - Li, Z. A1 - Jaberi, F.A. VL - To be published ER - TY - CONF T1 - Large -Scale Simulations of Incident Shock-Turbulent Boundary Layer Interactions T2 - 48th AIAA Aerospace Sciences Meeting Y1 - 2010 A1 - A. Jammalamadaka A1 - Jaberi, F.A. JF - 48th AIAA Aerospace Sciences Meeting CY - Orlando, FL ER - TY - JOUR T1 - Large-Eddy Simulations of Turbulent Methane Jet Flames with Filtered Mass Density Function JF - International Journal of Heat and Mass Transfer Y1 - 2010 A1 - Yaldizli, M. A1 - Mehravaran, K. A1 - Jaberi, F.A. KW - Filtered mass density function; PDF methods; Monte-Carlo simulations; Methane jet flames KW - LES AB -The filtered mass density function (FMDF) model (Jaberi et al. 1999 [1]) is employed for large eddy simulations (LES) of “high speed” partially-premixed methane jet flames with the “flamelet” and “finite-rate” kinetics models. The FMDF is the joint probability density function (PDF) of the scalars and is determined via the solution of a set of stochastic differential equations. The LES/FMDF is implemented using a highly scalable, parallel hybrid Eulerian–Lagrangian numerical scheme. The LES/FMDF results are shown to compare well with the experimental data for all flow conditions when “appropriate” reaction and mixing models are employed.

VL - 53 IS - 11-12 ER - TY - CONF T1 - Large-Scale Simulations of Supersonic Turbulent Reacting Flows T2 - 48th AIAA Aerospace Sciences Meeting Y1 - 2010 A1 - Li, Z. A1 - Jaberi, F.A. A1 - Banaeizadeh, A. AB -The scalar filtered mass density function (FMDF) is further developed and employed for large-eddy simulations (LES) of high speed turbulent flows in complex geometries. LES/FMDF is implemented via an efficient, hybrid numerical method. In this method, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved with a generalized, high-order, multi-block, compact differencing scheme. Turbulent mixing and combustion are modeled with the FMDF. The LES/FMDF method is used for simulations of isotropic turbulent flow in a piston-cylinder assembly, the flow in a shock tube and a supersonic co-axial helium-air jet. The critical role of pressure in the FMDF equation when applied to compressible flows is studied. It is shown that LES/FMDF is reliable and is able to simulate compressible turbulent mixing and combustion in supersonic flows.

JF - 48th AIAA Aerospace Sciences Meeting PB - AIAA CY - Orlando, FL ER - TY - CONF T1 - Multi-label Multiple Kernel Learning by Stochastic Approximation: Application to Visual Object Recognition T2 - Proceedings of Neural Information Processign Systems (NIPS 2010) Y1 - 2010 A1 - S.S.Bucak A1 - Jin, Rong A1 - Jain, Anil K. JF - Proceedings of Neural Information Processign Systems (NIPS 2010) ER - TY - CONF T1 - Numerical Investigations of Shock-Turbulence Interactions in a Planar Mixing Layer T2 - 48th AIAA Aerospace Sciences Meeting Y1 - 2010 A1 - Li, Z. A1 - Jaberi, F.A. AB -Direct numerical simulation (DNS) and large-eddy simulation (LES) of spatially developing supersonic mixing layer, interacting with an oblique shock wave are conducted with a new high-order Monotonicity-Preserving scheme. Without the incident shock, the mixing layer grows linearly and exhibits self-similar behavior after the transition. With the shock, significant small-scale turbulence is generated just behind the shock. With an increase in shock angle, the intensity of the shock-generated turbulence is increased and its peak position shifts away from the mixing layer centerline. The effects of turbulence on the shock are also shown to be very significant, such that normal shocklets and large adverse pressure gradients are created in some conditions. Comparison with the DNS data indicates that the LES with the modified kinetic energy viscosity (MKEV) subgrid stress model is able to predict the main features of the flow and shock-turbulence interactions.

JF - 48th AIAA Aerospace Sciences Meeting PB - AIAA CY - Orlando, FL ER - TY - CONF T1 - On the Use of Genetic Programming for Automated Refactoring and the Introduction of Design Patterns T2 - Proceedings of the 12th annual conference on Genetic and Evolutionary Computation Y1 - 2010 A1 - Jensen, A.C. A1 - Cheng, B.H.C. AB -Maintaining an object-oriented design for a piece of software is a difficult, time-consuming task. Prior approaches to au- tomated design refactoring have focused on making small, iterative changes to a given software design. However, such approaches do not take advantage of composition of design changes, thus limiting the richness of the refactoring strate- gies that they can generate. In order to address this prob- lem, this paper introduces an approach that supports com- position of design changes and makes the introduction of design patterns a primary goal of the refactoring process. The proposed approach uses genetic programming and soft- ware engineering metrics to identify the most suitable set of refactorings to apply to a software design. We illustrate the efficacy of this approach by applying it to a large set of published models, as well as a real-world case study.

JF - Proceedings of the 12th annual conference on Genetic and Evolutionary Computation PB - ACM ER - TY - CONF T1 - Efficient Multi-label Ranking for Multi-class Learning: Application to Object Recognition T2 - Proceedings of International conference on Computer Vision (ICCV 2009) Y1 - 2009 A1 - S.S.Bucak A1 - P.K. Mallapragada A1 - Jin, Rong A1 - Jain, Anil K. JF - Proceedings of International conference on Computer Vision (ICCV 2009) ER - TY - CONF T1 - Experimental and Computational Analysis of Fuel Mixing in a Low Pressure Direct Injection Gasoline Engine T2 - International Conference on Liquid Atomization and Spray Systems Y1 - 2009 A1 - S. Srivastava A1 - Jaberi, F.A. A1 - Harold Schock A1 - David Hung AB -An experimental and computational investigation of the fuel spray mixing in an optically accessible single-cylinder direct-injection engine under realistic operating conditions was performed. High speed flow visualization in the op- tical engine was performed with images taken at a rate of 10,000 frames per second. The numerical simulations were carried out using the KIVA-3V software, which uses the discrete particle method for modeling the spray, with the secondary droplet breakup modeled by the Taylor Analogy Breakup (TAB) model. The nozzle configuration, jet orientation, injection flow rate and other injection parameters were matched with the experimental conditions. The simulated spray patterns in the cylinder were shown to compare well with the fuel distribution images obtained from the high speed flow visualization. The computational and experimental results for the fuel impingement on the cyl- inder walls, piston and valves, and those for the spark plug wetting and evaporated fuel mixing indicate the strong dependency of the fuel-air mixing to the spray pattern.

JF - International Conference on Liquid Atomization and Spray Systems CY - Vail, Colorado ER - TY - CONF T1 - Large-Eddy Simulations of Turbulent Methane Jet Flames with Filtered Mass Density Function T2 - National Combustion Meeting Y1 - 2009 A1 - Yaldizli, M. A1 - Mehravaran, K. A1 - Jaberi, F.A. AB -The filtered mass density function (FMDF) model (Jaberi et al. 1999 [1]) is employed for large eddy simulations (LES) of “high speed” partially-premixed methane jet flames with the “flamelet” and “finite-rate” kinetics models. The FMDF is the joint probability density function (PDF) of the scalars and is determined via the solution of a set of stochastic differential equations. The LES/FMDF is implemented using a highly scalable, parallel hybrid Eulerian–Lagrangian numerical scheme. The LES/FMDF results are shown to compare well with the experimental data for all flow conditions when “appropriate” reaction and mixing models are employed.

JF - National Combustion Meeting PB - The Combustion Institute CY - Ann Arbor, Michigan ER - TY - CONF T1 - Large-Scale Simulations of High Speed Turbulent Flows T2 - 47th AIAA Aerospace Sciences Meeting Y1 - 2009 A1 - Li, Z. A1 - Jaberi, F.A. AB -This paper briefly describes a new class of high-order Monotonicity-Preserving (MP) finite difference methods recently developed for direct numerical simulation (DNS) and large-eddy simulation (LES) of high-speed turbulent flows. The MP method has been implemented together with high-order compact (COMP) and weighted essentially non- oscillatory (WENO) methods in a generalized three-dimensional (3D) code and has been applied to various 1D, 2D and 3D problems. For the LES, compressible versions of the gradient-based subgrid-scale closures are employed. Detailed and extensive analysis of various flows indicates that MP schemes have less numerical dissipation and faster grid convergence than WENO schemes. Simulations conducted with high-order MP schemes preserve sharp changes in flow variables without spurious oscillations and capture the turbulence at the smallest simulated scales. The non-conservative form of the scalar equation solved with MP schemes are shown to generate the same results as COMP schemes for supersonic mixing problems involving shock waves.

JF - 47th AIAA Aerospace Sciences Meeting PB - American Institute of Aeronautics and Astronautics CY - Orlando, FL ER - TY - CONF T1 - LES/FMDF of Spray Combustion in Internal Combustion Engines T2 - National Combustion Meeting Y1 - 2009 A1 - Banaeizadeh, A. A1 - Harold Schock A1 - Jaberi, F.A. AB -The two-phase filtered mass density function (FMDF) model is employed for large-eddy simulation (LES) of turbulent spray combustion in internal combustion (IC) engines. The LES/FMDF is implemented with an efficient, hybrid numerical method. In this method, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved with a generalized, high-order, multi-block, compact differencing scheme. The spray and the FMDF are implemented with Lagrangian methods. The LES/FMDF methodology has been used for simulations of turbulent combustion in a rapid compression machine (RCM) and in a direct-injection spark-ignition (DISI) engine. For both RCM and DISI engine, the complex interactions among turbulent velocity, fuel droplets and combustion are shown to be well captured with the LES/FMDF. The results for the DISI engine indicate that the size, velocity, evaporation and combustion of the sprayed fuel droplets are strongly affected by the unsteady, vortical motions generated by the incoming air during the intake stroke. In turn, the droplets are found to change the in-cylinder flow structure.

JF - National Combustion Meeting PB - The Combustion Institute CY - Ann Arbor, Michigan ER - TY - CONF T1 - A New Model for Numerical Simulations of Two-Phase Turbulent Combustion T2 - National Combustion Meeting Y1 - 2009 A1 - Li, Z. A1 - Jaberi, F.A. JF - National Combustion Meeting PB - National Combustion Meeting CY - Ann Arbor, MI ER - TY - CONF T1 - Numerical Simulation of a Direct-Injection Spark-Ignition Engine with Different Fuels T2 - SAE World Congress and Exhibit Y1 - 2009 A1 - S. Srivastava A1 - Harold Schock A1 - Jaberi, F.A. A1 - David Hung AB -This paper focuses on the numerical investigation of the mixing and combustion of ethanol and gasoline in a single-cylinder 3-valve direct-injection spark-ignition engine. The numerical simulations are conducted with the KIVA code with global reaction models. However, an ignition delay model mitigates some of the deficiencies of the global one-step reaction model and is implemented via a two-dimensional look-up table, which was created using available detailed kinetics models. Simulations demonstrate the problems faced by ethanol operated engines and indicate that some of the strategies used for emission control and downsizing of gasoline engines can be employed for enhancing the combustion efficiency of ethanol operated engines.

JF - SAE World Congress and Exhibit PB - SAE International CY - Detroit, Michigan ER - TY - JOUR T1 - Turbulence-Interface Interactions in a Two-Fluid Homogeneous Flow JF - Physics of Fluids Y1 - 2009 A1 - Li, Z. A1 - Jaberi, F.A. AB -The two-way interactions between the turbulent velocity field and the interface in an incompressible two-fluid homogeneous turbulent flow are studied with a recently developed Lagrangian–Eulerian interfacial particle level-set method. The numerical results confirm that the rate of change of the interface area is directly related to the work done by the surface tension force. While the surface tension damps the surrounding turbulence in the “interface stretching period” to oppose the increase in interface area, it is shown to actually increase the turbulent kinetic energy when the interface experiences compression. Additionally, the surface tension force is found to generate strong vortical motions close to the interface through the baroclinic torque effects. There is also an increase in strain rate and the viscous dissipation rate of turbulent kinetic energy in the interface region. The effect of interface on the surrounding turbulence appears primarily in the direction perpendicular to the interface. Analysis of the vorticity and kinetic energy equations indicates that the turbulence-interface interactions are strongly dependent on the fluids’ density ratio and the Weber number.

VL - 21 IS - 9 ER - TY - CONF T1 - Filtered Mass Density Function for Numerical Simulations of Spray Combustion T2 - 46th AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2008 A1 - Li, Z. A1 - Jaberi, F.A. A1 - Yaldizli, M. AB -This paper briefly describes our recent efforts on the modeling and numerical simulations of two-phase turbulent reacting flows in realistic combustion systems with a new large-eddy simulation (LES) model. The model is constructed based on the two-phase extension of scalar filtered mass density function (FMDF) and a Lagrangian-Eulerian- Lagrangian mathematical/numerical methodology. In this methodology, the “resolved” fluid velocity field is obtained by solving the filtered form of the compressible Navier-Stokes equations with a high-order finite difference scheme. The liquid (droplet) phase and scalar (temperature and species mass fractions) fields are both obtained by stochastic Lagrangian models. There are two-way interactions between the phases and all the Eulerian and Lagrangian fields. The LES/FMDF is used for systematic analysis of turbulent combustion in the spray-controlled dump combustor and double-swirl spray burner for various flow and spray parameters. The effects of fuel type, spray angle, mass loading ratio, droplet size distribution, fuel/air composition, wall, and inflow/outflow conditions on the combustion are investigated. It has been found that the main features of the turbulence and combustion are modified by changing the inflow/outflow conditions. The LES/FMDF results also confirm the significance of the spray parameters.

JF - 46th AIAA Aerospace Sciences Meeting and Exhibit PB - AIAA CY - Reno, Nevada ER - TY - JOUR T1 - A Hybrid Langrangian-Eulerian Particle-Level Set Method for numerical Simulations of Two-Fluid Turbulent Flows JF - International Journal for Numerical Methods in Fluids Y1 - 2008 A1 - Li, Z. A1 - Jaberi, F.A. A1 - Shih, T. I-P. KW - two-fluid turbulent flows; particle-level set method; interface tracking AB -A coupled Lagrangian interface-tracking and Eulerian level set (LS) method is developed and implemented for numerical simulations of two-fluid flows. In this method, the interface is identified based on the locations of notional particles and the geometrical information concerning the interface and fluid properties, such as density and viscosity, are obtained from the LS function. The LS function maintains a signed distance function without an auxiliary equation via the particle-based Lagrangian re-initialization technique. To assess the new hybrid method, numerical simulations of several ‘standard interface-moving’ problems and two-fluid laminar and turbulent flows are conducted. The numerical results are evaluated by monitoring the mass conservation, the turbulence energy spectral density function and the consistency between Eulerian and Lagrangian components. The results of our analysis indicate that the hybrid particle-level set method can handle interfaces with complex shape change, and can accurately predict the interface values without any significant (unphysical) mass loss or gain, even in a turbulent flow. The results obtained for isotropic turbulence by the new particle-level set method are validated by comparison with those obtained by the ‘zero Mach number’, variable-density method. For the cases with small thermal/mass diffusivity, both methods are found to generate similar results. Analysis of the vorticity and energy equations indicates that the destabilization effect of turbulence and the stability effect of surface tension on the interface motion are strongly dependent on the density and viscosity ratios of the fluids. Copyright q 2007 John Wiley & Sons, Ltd.

VL - 56 IS - 12 ER - TY - CONF T1 - Large Eddy Simulation of High Speed Turbulent Reacting Flows Y1 - 2008 A1 - Zhaorui, Li A1 - Banaeizadeh, A. A1 - Jaberi, F.A. CY - Hawaii ER - TY - CONF T1 - Large Eddy Simulations of Turbulent Flows in IC Engines T2 - ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) Y1 - 2008 A1 - Banaeizadeh, A. A1 - Afshari, A. A1 - Jaberi, F.A. A1 - H. Schock AB -A new computational methodology is developed and tested for large eddy simulation (LES) of turbulent flows in internal combustion (IC) engines. In this methodology, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved via a generalized, high-order, multi-block, compact differencing scheme and various subgrid-scale (SGS) stress closures. Both reacting and nonreacting flows with and without spray are considered. The LES models have been applied to a piston-cylinder assembly with a stationary open valve and harmonically moving flat piston. The flow in a direct-injection spark-ignition (DISI) engine is also considered. It is observed that during the intake stroke of the engine operation, large-scale unsteady turbulent flow motions are developed behind the intake valves. The physical features of these turbulent motions and the ability of LES to capture them are studied and tested by simulating the flow in a simple configuration involving a stationary valve. The flow statistics predicted by LES are shown to compare well with the available experimental data. The DISI configuration includes all the complexities involved in a realistic single-cylinder IC engine, such as the complex geometry, moving valves, moving piston, spray and combustion. The spray combustion is simulated with the recently developed two-phase filtered mass density (FMDF) model.

JF - ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2008) PB - ASME CY - Brooklyn, New York SN - 978-0-7918-4327-7 ER - TY - CONF T1 - Large Eddy Simulations of Two-Phase Turbulent Reacting Flows T2 - 46TH AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2008 A1 - Jaberi, F.A. A1 - Li, Z. JF - 46TH AIAA Aerospace Sciences Meeting and Exhibit PB - AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS CY - Reno, Nevada ER - TY - JOUR T1 - Large-Eddy Simulation of a Dispersed Particle-Laden Turbulent Round Jet JF - International Journal of Heat and Mass Transfer Y1 - 2008 A1 - Almeida, T. A1 - Jaberi, F.A. KW - Particle-laden jet; dilute KW - two-phase flows; turbulent jet; LES AB -The numerical results obtained by large-eddy simulation (LES) of a particle-laden axisymmetric turbulent jet are compared with the available experimental data. The results indicate that with a new stochastic subgrid-scale (SGS) closure, the effects of the particles on the carrier gas and those of the carrier gas on the particles are correctly captured by the LES. Additional numerical experiments are conducted and used to investigate the effects of particle size, mass-loading ratio, and other flow/particle parameters on the statistics of both the carrier gas phase and the particle dispersed phase.

VL - 51 IS - 3-4 ER - TY - JOUR T1 - Large-Eddy Simulation of Turbulent Flow in an Axisymmetric Dump Combustor JF - AIAA Journal Y1 - 2008 A1 - Afshari, A. A1 - Jaberi, F.A. KW - combustion KW - Gas turbine; modeling; combustion chamber; Monte Carlo method; Lagragian Method; turbulent flow; large eddy simulation AB -A hybrid Eulerian–Lagrangian, mathematical/computational methodology is developed and evaluated for large- eddy simulations of turbulent combustion in complex geometries. The formulation for turbulence is based on the standard subgrid-scale stress models. The formulation for subgrid-scale combustion is based on the filtered mass density function and its equivalent stochastic Lagrangian equations. An algorithm based on high-order compact differencing on generalized multiblock grids is developed for numerical solution of the coupled Eulerian–Lagrangian equations. The results obtained by large-eddy simulations/filtered mass density function show the computational method to be more efficient than existing methods for similar hybrid systems. The consistency, convergence, and accuracy of the filtered mass density function and its Lagrangian–Monte Carlo solver is established for both reacting and nonreacting flows in a dump combustor. The results show that the finite difference and the Monte Carlo numerical methods employed are both accurate and consistent. The results for a reacting premixed dump combustor also agree well with available experimental data. Additionally, the results obtained for other nonreacting turbulent flows are found to be in good agreement with the experimental and high-order numerical data. Filtered mass density function simulations are performed to examine the effects of boundary conditions, subgrid-scale models, as well as physical and geometrical parameters on dump-combustor flows. The results generated for combustors with and without an inlet nozzle are found to be similar as long as appropriate boundary conditions are employed.

VL - 46 IS - 7 ER - TY - JOUR T1 - The Structure of Partially-Premixed Methane Flames in High Intensity Turbulent Flows JF - Combustion and Flame Y1 - 2008 A1 - Yaldizli, M. A1 - Mohammad, H. A1 - Mehravaran, K. A1 - Jaberi, F.A. KW - DNS; Methane combustion KW - turbulent reacting flows; partially premixed flames; reduced chemistry models AB -Direct numerical simulations (DNS) are conducted to study the structure of partially premixed and non-premixed methane flames in high-intensity two-dimensional isotropic turbulent flows. The results obtained via “flame normal analysis” show local extinction and reignition for both non-premixed and partially premixed flames. Dynamical analysis of the flame with a Lagrangian method indicates that the time integrated strain rate characterizes the finite-rate chemistry effects and the flame extinction better than the strain rate. It is observed that the flame behavior is affected by the “pressure-dilatation” and “viscous-dissipation” in addition to strain rate. Consistent with previous studies, high vorticity values are detected close to the reaction zone, where the vorticity generation by the “baroclinic torque” was found to be significant. The influences of (initial) Reynolds and Damköhler numbers, and various air–fuel premixing levels on flame and turbulence variables are also studied. It is observed that the flame extinction occurs similarly in flames with different fuel–air premixing. Our simulations also indicate that the CO emission increases as the partial premixing of the fuel with air increases. Higher values of the temperature, the OH mass fraction and the CO mass fraction are observed within the flame zone at higher Reynolds numbers.

VL - 154 IS - 4 ER - TY - CONF T1 - Filtered Mass Density Function for Numerical Simulations of Spray Combustion T2 - 46th AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2007 A1 - Yaldizli, M. A1 - Li, Z. A1 - Jaberi, F.A. AB -This paper briefly describes our recent efforts on the modeling and numerical simulations of two-phase turbulent reacting flows in realistic combustion systems with a new large-eddy simulation (LES) model. The model is constructed based on the two-phase extension of scalar filtered mass density function (FMDF) and a Lagrangian-Eulerian- Lagrangian mathematical/numerical methodology. In this methodology, the “resolved” fluid velocity field is obtained by solving the filtered form of the compressible Navier-Stokes equations with a high-order finite difference scheme. The liquid (droplet) phase and scalar (temperature and species mass fractions) fields are both obtained by stochastic Lagrangian models. There are two-way interactions between the phases and all the Eulerian and Lagrangian fields. The LES/FMDF is used for systematic analysis of turbulent combustion in the spray-controlled dump combustor and double-swirl spray burner for various flow and spray parameters. The effects of fuel type, spray angle, mass loading ratio, droplet size distribution, fuel/air composition, wall, and inflow/outflow conditions on the combustion are investigated. It has been found that the main features of the turbulence and combustion are modified by changing the inflow/outflow conditions. The LES/FMDF results also confirm the significance of the spray parameters.

JF - 46th AIAA Aerospace Sciences Meeting and Exhibit PB - AIAA CY - Reno, Nevada ER - TY - CONF T1 - LES/FMDF of Turbulent Combustion in Complex Flow Systems T2 - 45th AIAA Aerospace Sciences Meeting and Exhibit Y1 - 2007 A1 - Afshari, A. A1 - Jaberi, F.A. A1 - Shih, T. I-P. AB -A high-order Lagrangian/Eulerian method based on the the filtered mass density func- tion (FMDF) for subgrid-scale (SGS) combustion closure was developed to perform large eddy simulation (LES) of turbulent reacting flows in complex geometrical configurations in multi-block structured grids. In particular, an efficient algorithm has been developed to search and locate particles in multi-block, hexahedral-structured grid system. Also, the consistency, convergence, and accuracy of the FMDF and the Monte Carlo solution of its equivalent stochastic differential equations were assessed. The consistency between Eulerian and Lagrangian fields were established for a reacting flow in a dump combustor. The results obtained for a reacting flow in an axisymmetric, premixed dump-combustor, were found to compare favorably with measured experimental data.

JF - 45th AIAA Aerospace Sciences Meeting and Exhibit PB - AIAA CY - Reno, Nevada ER - TY - CONF T1 - A New Model for Large Eddy Simulations of Multi-Phase Turbulent Combustion T2 - Proceedings of the 43rd AIAA/ASME/SAI/ASEE Joint Propulsion Conference Y1 - 2007 A1 - Yaldizli, M. A1 - Li, Z. A1 - J.A. Jaberi AB -Numerical simulations of a spray-controlled lean premixed dump combustor are con- ducted via a two-phase large eddy simulation (LES) methodology. In this methodology, the velocity field is obtained by a high-order finite difference method. The subgrid gas- liquid combustion closure is based on the two-phase filtered mass density function (FMDF) method and the spray is modeled with a Lagrangian scheme. The effects of spray, fuel/air composition, and inflow/outflow conditions on the combustion are investigated. It has been found that the main features of the turbulence and combustion inside the dump combustor are very differently modified by the spray for different spray parameters. The LES/FMDF results also indicate the significance of the inflow and outflow conditions.

JF - Proceedings of the 43rd AIAA/ASME/SAI/ASEE Joint Propulsion Conference PB - AIAA/ASME/SAI/ASEE CY - Cincinnati, Ohio ER - TY - Generic T1 - Numerical Simulations of Two-Phase Turbulent Combustion in Spray Burners T2 - ASME Conference Proceedings, Computers and Information in Engineering Conference Y1 - 2007 A1 - Li, Z. A1 - Yaldizli, M. A1 - Jaberi, F.A. AB -The complex interactions among turbulence, combustion and spray in liquid-fuel burners are modeled and simulated via a new two-phase Lagrangian-Eulerian-Lagrangian large eddy simulation (LES) methodology. In this methodology, the spray is modeled with a Lagrangian mathematical/computational method which allows two-way mass, momentum and energy coupling between phases. The subgrid gas-liquid combustion is based on the two-phase filtered mass density function (FMDF) that has several advantages over “conventional” two-phase combustion models. The LES/FMDF is employed in conjunction with non-equilibrium reaction and droplet models. Simulations of turbulent combustion in a spray-controlled double-swirl burner are conducted via LES/FMDF. The generated results are used for better understanding of spray combustion in realistic turbulent flow configurations. The effects of spray angle, mass loading ratio, fuel type, droplet size distribution, wall and inflow/outflow conditions on the flow and combustion are investigated. The LES/FMDF predictions are shown to be consistent with the experimental results.

JF - ASME Conference Proceedings, Computers and Information in Engineering Conference PB - ASME CY - Las Vegas, Nevada SN - 0-7918-4803-5 ER - TY - JOUR T1 - Shape and Structure of N = Z 64Ge: Electromagnetic Transition Rates from the Application ￼of the Recoil Distance Method to a Knockout Reaction JF - PHYSICAL REVIEW LETTERS Y1 - 2007 A1 - K. Starosta A1 - A. Dewald A1 - A. Dunomes A1 - P. Adrich A1 - A.M. Amthor A1 - T. Baumann A1 - D. Bazin A1 - M. Bowen A1 - B. A. Brown A1 - A. Chester A1 - A. Gade A1 - D. Galaviz A1 - T. Glasmacher A1 - T. Ginter A1 - M. Hausmann A1 - M. Horoi A1 - J. Jolie A1 - B. Melon A1 - D. Miller A1 - V. Moeller A1 - R.P. Norris A1 - T. Pissulla A1 - M. Portillo A1 - W. Rother A1 - Y. Shimbara A1 - A. Stolz A1 - C. Vaman A1 - P. Voss A1 - D. Weisshaar A1 - V. Zelevinsky VL - 99 UR - http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.042503 ER - TY - JOUR T1 - Ab initio determination of solid-state nanostructure JF - Nature Y1 - 2006 A1 - P. Juhás A1 - D. M. Cherba A1 - P. M. Duxbury A1 - W. F. Punch A1 - S. J. L. Billinge AB -Advances in materials science and molecular biology followed rapidly from the ability to characterize atomic structure using single crystals1, 2, 3, 4. Structure determination is more difficult if single crystals are not available5. Many complex inorganic materials that are of interest in nanotechnology have no periodic long-range order and so their structures cannot be solved using crystallographic methods6. Here we demonstrate that ab initio structure solution of these nanostructured materials is feasible using diffraction data in combination with distance geometry methods. Precise, sub-ångström resolution distance data are experimentally available from the atomic pair distribution function (PDF)6, 7. Current PDF analysis consists of structure refinement from reasonable initial structure guesses6, 7 and it is not clear, a priori, that sufficient information exists in the PDF to obtain a unique structural solution. Here we present and validate two algorithms for structure reconstruction from precise unassigned interatomic distances for a range of clusters. We then apply the algorithms to find a unique, ab initio, structural solution for C60 from PDF data alone. This opens the door to sub-ångström resolution structure solution of nanomaterials, even when crystallographic methods fail.

VL - 440 ER - TY - JOUR T1 - Direct Numerical Simulations of a Planar Jet Laden with Evaporating Droplets JF - International Journal of Heat and Mass Transfer Y1 - 2006 A1 - Almeida, T. A1 - Jaberi, F.A. KW - droplet-laden turbulent jet; two-phase planar jet; droplet evaporation; DNS AB -A direct numerical simulation (DNS) study is conducted on the various aspects of phase interactions in a planar turbulent gas-jet laden with non-evaporative and evaporative liquid droplets. A compressible computational model utilizing a finite difference scheme for the carrier gas and a Lagrangian solver for the droplet phase is used to conduct the numerical experiments. The effects of droplet time constant, mass-loading and mass/momentum/energy coupling between phases on droplet and gas-jet fields are investigated. Significant changes in velocity, temperature, density and turbulence production on account of the coupling between the liquid and gas phases are observed in non-isothermal jets with evaporating droplets. Most of these changes are attributed to the density stratification in the carrier gas that is caused by droplet momentum and heat transfer.

VL - 49 IS - 13-14 ER - TY - JOUR T1 - The ground state of chargeless fermions with finite magnetic moment JF - Journal of Physics A: Mathematical and General Y1 - 2006 A1 - S. D. Mahanti A1 - Sudhanshu S. Jha AB -We consider the ground state of a system of chargeless fermions, such as neutrinos, of mass m and magnetic moment m interacting through long-range magnetic dipole interaction, within the framework of a {Hartree-Fock} variational approach. At high densities the uniform paramagnetic state becomes unstable towards a ferromagnetic state with quadrupolar deformation of the Fermi surface. The exchange energy which is attractive dominates the repulsive kinetic energy. If we let the density be a variable, then above a certain density the system will collapse to an infinite density state unless another short-range interaction stops the collapse. In the case of large deformations, the possibility of a purely dipolar deformation exists.

VL - 39 IS - 6 ER - TY - JOUR T1 - Half-life and spin of 60Mng JF - Physical Review C Y1 - 2006 A1 - S. N. Liddick A1 - P. F. Mantica A1 - B. A. Brown A1 - M. P. Carpenter A1 - A. D. Davies A1 - M. Horoi A1 - R. V. F. Janssens A1 - A. C. Morton A1 - W. F. Mueller A1 - J. Pavan A1 - H. Schatz A1 - A. Stolz A1 - S. L. Tabor A1 - B. E. Tomlin A1 - M. Wiedeking AB -A value of 0.28±0.02 s has been deduced for the half-life of the ground state of {60Mn,} in sharp contrast to the previously adopted value of 51±6 s. Access to the low-spin {60Mn} ground state was accomplished via β decay of the 0+ {60Cr} parent nuclide. New low-energy states in {60Mn} have been identified from β-delayed γ-ray spectroscopy. The new, shorter half-life of {60Mng} is not suggestive of isospin-forbidden β decay, and new spin and parity assignments of 1+ and 4+ have been adopted for the ground and isomeric β-decaying states, respectively, of {60Mn.}

VL - 73 IS - 4 N1 - Copyright {(C)} 2010 The American Physical Society; Please report any problems to prola@aps.org ER - TY - JOUR T1 - Half-life and spin of 60Mng JF - PHYSICAL REVIEW C Y1 - 2006 A1 - S. N. Liddick A1 - P. F. Mantica A1 - B. A. Brown A1 - M. P. Carpenter A1 - A. D. Davies A1 - M. Horoi A1 - R. V. F. Janssens A1 - A. C. Morton A1 - W. F. Mueller A1 - J. Pavan A1 - H. Schatz A1 - A. Stolz A1 - S. L. Tabor A1 - B. E. Tomlin A1 - M. Wiedeking VL - 73 UR - http://journals.aps.org/prc/abstract/10.1103/PhysRevC.73.044322 IS - 4 ER - TY - Generic T1 - Coupled Cluster Approaches to Nuclei, Ground States and Excited States T2 - Key Topics in Nuclear Structure, Proceedings of the 8th International Spring Seminar on Nuclear Physics Y1 - 2005 A1 - Piotr Piecuch A1 - D. J. Dean A1 - M. Jhorth-Jensen A1 - K. Kowalski A1 - T. Papenbrock A1 - M. Wloch AB -We present recent coupled-cluster studies of nuclei, with an emphasis on ground state and excited states of closed shell nuclei. Perspectives for future studies are delineated.

JF - Key Topics in Nuclear Structure, Proceedings of the 8th International Spring Seminar on Nuclear Physics CY - Paestum, Italy ER -