Albuquerque, NM, United States
Albuquerque, NM, United States

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Agency: GTR | Branch: EPSRC | Program: | Phase: Training Grant | Award Amount: 3.94M | Year: 2014

The achievements of modern research and their rapid progress from theory to application are increasingly underpinned by computation. Computational approaches are often hailed as a new third pillar of science - in addition to empirical and theoretical work. While its breadth makes computation almost as ubiquitous as mathematics as a key tool in science and engineering, it is a much younger discipline and stands to benefit enormously from building increased capacity and increased efforts towards integration, standardization, and professionalism. The development of new ideas and techniques in computing is extremely rapid, the progress enabled by these breakthroughs is enormous, and their impact on society is substantial: modern technologies ranging from the Airbus 380, MRI scans and smartphone CPUs could not have been developed without computer simulation; progress on major scientific questions from climate change to astronomy are driven by the results from computational models; major investment decisions are underwritten by computational modelling. Furthermore, simulation modelling is emerging as a key tool within domains experiencing a data revolution such as biomedicine and finance. This progress has been enabled through the rapid increase of computational power, and was based in the past on an increased rate at which computing instructions in the processor can be carried out. However, this clock rate cannot be increased much further and in recent computational architectures (such as GPU, Intel Phi) additional computational power is now provided through having (of the order of) hundreds of computational cores in the same unit. This opens up potential for new order of magnitude performance improvements but requires additional specialist training in parallel programming and computational methods to be able to tap into and exploit this opportunity. Computational advances are enabled by new hardware, and innovations in algorithms, numerical methods and simulation techniques, and application of best practice in scientific computational modelling. The most effective progress and highest impact can be obtained by combining, linking and simultaneously exploiting step changes in hardware, software, methods and skills. However, good computational science training is scarce, especially at post-graduate level. The Centre for Doctoral Training in Next Generation Computational Modelling will develop 55+ graduate students to address this skills gap. Trained as future leaders in Computational Modelling, they will form the core of a community of computational modellers crossing disciplinary boundaries, constantly working to transfer the latest computational advances to related fields. By tackling cutting-edge research from fields such as Computational Engineering, Advanced Materials, Autonomous Systems and Health, whilst communicating their advances and working together with a world-leading group of academic and industrial computational modellers, the students will be perfectly equipped to drive advanced computing over the coming decades.

Pitz W.J.,Lawrence Livermore National Laboratory | Mueller C.J.,Sandia National Laboratories
Progress in Energy and Combustion Science | Year: 2011

There has been much recent progress in the area of surrogate fuels for diesel. In the last few years, experiments and modeling have been performed on higher molecular weight components of relevance to diesel fuel such as n-hexadecane (n-cetane) and 2,2,4,4,6,8,8-heptamethylnonane (iso-cetane). Chemical kinetic models have been developed for all the n-alkanes up to 16 carbon atoms. Also, there has been experimental and modeling work on lower molecular weight surrogate components such as n-decane and n-dodecane that are most relevant to jet fuel surrogates, but are also relevant to diesel surrogates where simulation of the full boiling point range is desired. For two-ring compounds, experimental work on decalin and tetralin recently has been published. For esters, kinetic mechanisms for compounds of lower molecular weights but similar to those found in typical biodiesel blendstocks also have been published. For multi-component surrogate fuel mixtures, recent work on modeling of these mixtures and comparisons to real diesel fuel is reviewed. Detailed chemical kinetic models for surrogate fuels are very large in size, so it is noteworthy that significant progress also has been made in improving the mechanism reduction tools that are needed to make these large models practicable in multi-dimensional reacting flow simulations of diesel combustion. Nevertheless, major research gaps remain. In the case of iso-alkanes, there are experiments and modeling work on only one of relevance to diesel: iso-cetane. Also, the iso-alkanes in diesel are lightly branched and no detailed chemical kinetic models or experimental investigations are available for such compounds. More components are needed to fill out the iso-alkane boiling point range. For the aromatic class of compounds, there has been little work for compounds in the boiling point range of diesel. Most of the new work has been on alkyl aromatics that are of the range C7-C9, below the C10-C20 range that is needed. For the chemical classes of cycloalkanes and esters, experiments and modeling on higher molecular weight components are warranted. Finally for multi-component surrogates needed to treat real diesel, the inclusion of higher molecular weight components is needed in models and experimental investigations.

Agency: Department of Defense | Branch: Missile Defense Agency | Program: STTR | Phase: Phase II | Award Amount: 996.70K | Year: 2015

Leveraging the results of our Phase I work, the Torch Team proposes to execute laboratory-based experiments to elucidate fundamental micro-debris formation mechanisms to improve optical modeling of impacts. Optical signatures from impacts collected over the last decade have identified definitive micro-debris parameter trends. However, current theories have difficulty reproducing these optical observations. Our Phase II work plan includes the development of innovative particle sizing instrumentation. Moreover, a novel experiment will be conducted to validate radiometric inversion methodologies for determining micro-debris properties in ground and flight tests, thereby leveraging existing optical data collected on impacts. Our proposed experimental approach will address critical micro-debris characterization data gaps in a timely and cost effective manner to improve hypervelocity impact electro-optic/infrared (EO/IR) modeling. Approved for Public Release, 15-MDA-8303 (1 July 15)

Agency: National Science Foundation | Branch: | Program: STTR | Phase: Phase I | Award Amount: 225.00K | Year: 2016

This Small Business Technology Transfer Phase I project will advance the development of new portable gas analysis systems. Portable analysis systems can provide timely information about the surroundings, leading to better decisions in critical situations. For law enforcement, a portable detector based on the proposed technology will enable officers to focus an investigation on specific targets, whether narcotics or explosives. Likewise, for military and civil defense operations, trace explosives can be detected even when the bulk of the material is well concealed. A portable system with the proposed detector will easily be able to identify and quantify chemical warfare agents and pesticides at single part-per-billion levels in complex backgrounds. With precise agent detection at these low levels, the users of these systems will have better information and more time to act on that information. In agriculture, a better detector will lead to a more judicious use of pesticides and thereby increase their effectiveness while reducing human exposure. Considering all of the potential applications, the proposed work could lead to significant advancements in a $600 million segment of the $2 billion annual gas detection market. The intellectual merit of this project is based on the years of work that Sandia National Laboratories and Defiant Technologies have invested in the development of micro components and systems for chemical detection. The proposal objective is to develop a new ionization source that can replace radioactive materials, and other larger and more power hungry thermionic sources. The new thermionic ionization source will use micro-electro-mechanical systems (MEMS) fabrication techniques to form a millimeter-scale heating element that operates efficiently at 600 degrees C. New techniques to formulate and deposit low function work materials on these heaters will be developed and exploited to construct the ionization sources. The research will entail an exploration of alkali metal formulations for the low-work function material, heater fabrication for longevity, and source operating conditions for possible failure mechanisms. At the end of this Phase I effort, the goal is to develop an ionization source that can be coupled with portable gas chromatograph and portable ion mobility systems for the detection and analysis of explosives, chemical warfare agents, pesticides, and narcotics.

Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 911.40K | Year: 2016

During Phase I and Phase II, M4 Engineering, Inc. and Sandia National Laboratories have created a unique bonded joint analysis methodology and associated software. During Phase II.5, the developed techniques will be further enhanced and a fully functional commercial analysis code (SIMULIA/Abaqus) plug-in will be created. The software plug-in will make the advanced technology accessible to all levels of practicing engineers via integrated pre- and post-processing modules. The technology is based upon a world class nonlinear constitutive equation for polymers developed over a decade at Sandia. A two-pronged approach consisting of concise surrogate models (i.e., traction-separation interface models) for design and analysis and high fidelity models that can be used along with experimental data for surrogate model parameterization will provide the Navy a comprehensive bond modeling method. During Phase I and Phase II, ductile and brittle adhesives for metal bonding have been studied. The upcoming Phase II.5 work will include looking at an additional adhesive, as well as composite substrates. Hence, a key part of this work will also include an experimental program to populate the high fidelity models and validate the surrogate traction-separation models.

Leung K.,Sandia National Laboratories
Journal of Physical Chemistry C | Year: 2012

Density functional theory and ab initio molecular dynamics simulations are applied to investigate the initial steps of ethylene carbonate (EC) decomposition on spinel Li 0.6Mn 2O 4(100) surfaces. EC is a key component of the electrolyte used in lithium ion batteries. We predict a slightly exothermic EC bond-breaking event on this oxide facet, which facilitates subsequent EC oxidation and proton transfer to the oxide surface. Both the proton and the partially decomposed EC fragment weaken the Mn-O ionic bonding network. Implications for an interfacial film made of decomposed electrolyte on cathode surfaces, and Li xMn 2O 4 dissolution during power cycling, are discussed. © 2012 American Chemical Society.

Stavila V.,Sandia National Laboratories | Talin A.A.,Sandia National Laboratories | Allendorf M.D.,Sandia National Laboratories
Chemical Society Reviews | Year: 2014

Metal-organic frameworks (MOFs) are a class of hybrid materials with unique optical and electronic properties arising from rational self-assembly of the organic linkers and metal ions/clusters, yielding myriads of possible structural motifs. The combination of order and chemical tunability, coupled with good environmental stability of MOFs, are prompting many research groups to explore the possibility of incorporating these materials as active components in devices such as solar cells, photodetectors, radiation detectors, and chemical sensors. Although this field is only in its incipiency, many new fundamental insights relevant to integrating MOFs with such devices have already been gained. In this review, we focus our attention on the basic requirements and structural elements needed to fabricate MOF-based devices and summarize the current state of MOF research in the area of electronic, opto-electronic and sensor devices. We summarize various approaches to designing active MOFs, creation of hybrid material systems combining MOFs with other materials, and assembly and integration of MOFs with device hardware. Critical directions of future research are identified, with emphasis on achieving the desired MOF functionality in a device and establishing the structure-property relationships to identify and rationalize the factors that impact device performance. This journal is © the Partner Organisations 2014.

Sheps L.,Sandia National Laboratories
Journal of Physical Chemistry Letters | Year: 2013

We present the time-resolved UV absorption spectrum of the B̃ ( 1A′) ← X̃ (1A′) electronic transition of formaldehyde oxide, CH2OO, produced by the reaction of CH2I radicals with O2. In contrast to its UV photodissociation action spectrum, the absorption spectrum of formaldehyde oxide extends to longer wavelengths and exhibits resolved vibrational structure on its low-energy side. Chemical kinetics measurements of its reactivity establish the identity of the absorbing species as CH2OO. Separate measurements of the initial CH2I radical concentration allow a determination of the absolute absorption cross section of CH2OO, with the value at the peak of the absorption band, 355 nm, of σabs = (3.6 ± 0.9) × 10-17 cm2. The difference between the absorption and action spectra likely arises from excitation to long-lived B̃ (1A′) vibrational states that relax to lower electronic states by fluorescence or nonradiative processes, rather than by photodissociation. © 2013 American Chemical Society.

Leonard F.,Sandia National Laboratories | Talin A.A.,U.S. National Institute of Standards and Technology
Nature Nanotechnology | Year: 2011

Existing models of electrical contacts are often inapplicable at the nanoscale because there are significant differences between nanostructures and bulk materials arising from unique geometries and electrostatics. In this Review, we discuss the physics and materials science of electrical contacts to carbon nanotubes, semiconductor nanowires and graphene, and outline the main research and development challenges in the field. We also include a case study of gold contacts to germanium nanowires to illustrate these concepts. © 2011 Macmillan Publishers Limited. All rights reserved.

Leung K.,Sandia National Laboratories
Journal of Physical Chemistry C | Year: 2013

We review recent ab initio molecular dynamics studies of electrode/electrolyte interfaces in lithium ion batteries. Our goals are to introduce experimentalists to simulation techniques applicable to models which are arguably most faithful to experimental conditions so far, and to emphasize to theorists that the inherently interdisciplinary nature of this subject requires bridging the gap between solid and liquid state perspectives. We consider liquid ethylene carbonate (EC) decomposition on lithium intercalated graphite, lithium metal, oxide-coated graphite, and spinel manganese oxide surfaces. These calculations are put in the context of more widely studied water-solid interfaces. Our main themes include kinetically controlled two-electron-induced reactions, the breaking of a previously much neglected chemical bond in EC, and electron tunneling. Future work on modeling batteries at atomic length scales requires capabilities beyond state-of-the-art, which emphasizes that applied battery research can and should drive fundamental science development. © 2012 American Chemical Society.

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