Publications

Results 8401–8450 of 101,000

Search results

Jump to search filters

Recrystallization, melting, and erosion of dispersoid-strengthened tungsten materials during exposure to DIII-D plasmas

Kolasinski, Robert; Coburn, Jonathan D.; Truong, Dinh D.; Watkins, Jonathan G.; Abrams, Tyler; Fang, Z.Z.; Nygren, Richard E.; Leonard, Anthony; Ren, Jun; Wang, Huiqian; Whaley, Josh; Bykov, Igor; Glass, Fenton; Herfindal, Jeffrey; Hood, Ryan T.; Lasnier, Charles; Marini, Claudio; Mclean, Adam; Moser, Auna; Nishimoto, Ryan K.; Sugar, Joshua D.; Wilcox, Robert; York, Warren

Abstract not provided.

More Details
TYPE Conference Presentation YEAR 2022
DOIOSTI

Nonlinear Elongation Flows in Associating Polymer Melts: From Homogeneous to Heterogeneous Flow

Physical Review X

Mohottalalage, Supun S.; Senanayake, Manjula; Clemmer, Joel T.; Perahia, Dvora; Grest, Gary S.; O'Connor, Thomas

Response to elongational flow is fundamental to soft matter and directly impacts new developments in a broad range of technologies form polymer processing and microfluidics to controlled flow in biosystems. Of particular significance are the effects of elongational flow on self-assembled systems where the interactions between the fundamental building blocks control their adaptation. Here we probe the effects of associating groups on the structure and dynamics of linear polymer melts in uniaxial elongation using molecular dynamics simulations. We study model polymers with randomly incorporated backbone associations with interaction strengths varying from 1kBT to 10kBT. These associating groups drive the formation of clusters in equilibrium with an average size that increases with interaction strength. Flow drives these clusters to continuously break and reform as chains stretch. These flow-driven cluster dynamics drive a qualitative transition in polymer elongation dynamics from homogeneous to nanoscale localized yield and cavitation as the association strength increases.

More Details
TYPE Journal Article YEAR 2022
DOIOSTIScopus

The Portals 4.3 Network Programming Interface

Schonbein, Whit; Barrett, Brian W.; Brightwell, Ronald B.; Grant, Ryan E.; Hemmert, Karl S.; Bays, Nathan R.; Underwood, Keith; Riesen, Rolf; Hoefler, Torsten; Barbe, Mathieu; Suraty Filho, Luiz H.; Ratchov, Alexandre; Maccabe, Arthur B.

This report presents a specification for the Portals 4 network programming interface. Portals 4 is intended to allow scalable, high-performance network communication between nodes of a parallel computing system. Portals 4 is well suited to massively parallel processing and embedded systems. Portals 4 represents an adaption of the data movement layer developed for massively parallel processing platforms, such as the 4500-node Intel TeraFLOPS machine. Sandia's Cplant cluster project motivated the development of Version 3.0, which was later extended to Version 3.3 as part of the Cray Red Storm machine and XT line. Version 4 is targeted to the next generation of machines employing advanced network interface architectures that support enhanced offload capabilities.

More Details
TYPE SAND Report YEAR 2022
DOIOSTI

Neutron backscatter edges as a diagnostic of burn propagation

Physics of Plasmas

Crilly, A.J.; Appelbe, B.D.; Mannion, Owen; Forrest, C.J.; Knauer, J.P.; Schlossberg, D.J.; Hartouni, E.P.; Moore, A.S.; Chittenden, J.P.

High gain in hotspot-ignition inertial confinement fusion (ICF) implosions requires the propagation of thermonuclear burn from a central hotspot to the surrounding cold dense fuel. As ICF experiments enter the burning plasma regime, diagnostic signatures of burn propagation must be identified. In previous work [A. J. Crilly et al., Phys. Plasmas 27(1), 012701 (2020)], it has been shown that the spectral shape of the neutron backscatter edges is sensitive to the dense fuel hydrodynamic conditions. The backscatter edges are prominent features in the ICF neutron spectrum produced by the 180° scattering of primary deuterium–tritium fusion neutrons from ions. In this work, synthetic neutron spectra from radiation-hydrodynamics simulations of burning ICF implosions are used to assess the backscatter edge analysis in a propagating burn regime. Significant changes to the edge's spectral shape are observed as the degree of burn increases, and a simplified analysis is developed to infer scatter-averaged fluid velocity and temperature. The backscatter analysis offers direct measurement of the increased dense fuel temperatures that result from burn propagation.

More Details
TYPE Journal Article YEAR 2022
DOIOSTI

Differentially Private Synthesis and Sharing of Network Data Via Bayesian Exponential Random Graph Models

Journal of Survey Statistics and Methodology

Eugenio, Evercita C.; Liu, Fang; Jin, Ick H.; Mc Bowen, Clairekay

Network data often contain sensitive relational information. One approach to protecting sensitive information while offering flexibility for network analysis is to share synthesized networks based on the information in originally observed networks. We employ differential privacy (DP) and exponential random graph models (ERGMs) and propose the DP-ERGM method to synthesize network data. We apply DP-ERGM to two real-world networks. We then compare the utility of synthesized networks generated by DP-ERGM, the DyadWise Randomized Response (DWRR) approach, and the Synthesis through Conditional distribution of Edge given nodal Attribute (SCEA) approach. In general, the results suggest that DP-ERGM preserves the original information significantly better than two other approaches in network structural statistics and inference for ERGMs and latent space models. Furthermore, DP-ERGM satisfies node DP through modeling the global network structure with ERGM, a stronger notion of privacy than the edge DP under which DWRR and SCEA operate.

More Details
TYPE Journal Article YEAR 2022
DOIOSTIScopus

A Taxonomy of Small Markovian Errors

PRX Quantum

Blume-Kohout, Robin; Da Silva, Marcus P.; Nielsen, Erik N.; Proctor, Timothy J.; Rudinger, Kenneth M.; Sarovar, Mohan; Young, Kevin

Errors in quantum logic gates are usually modeled by quantum process matrices (CPTP maps). But process matrices can be opaque and unwieldy. We show how to transform the process matrix of a gate into an error generator that represents the same information more usefully. We construct a basis of simple and physically intuitive elementary error generators, classify them, and show how to represent the error generator of any gate as a mixture of elementary error generators with various rates. Finally, we show how to build a large variety of reduced models for gate errors by combining elementary error generators and/or entire subsectors of generator space. We conclude with a few examples of reduced models, including one with just 9N2 parameters that describes almost all commonly predicted errors on an N-qubit processor.

More Details
TYPE Journal Article YEAR 2022
DOIOSTIScopus
Results 8401–8450 of 101,000
Results 8401–8450 of 101,000
Top