Publications

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This document outlines a statistical framework for establishing a shelf-life program for components whose performance is measured by the value of a continuous variable such as voltage or function time. The approach applies to both single measurement devices and repeated measurement devices, although additional process control charts may be useful in the case of repeated measurements. The approach is to choose a sample size that protects the margin associated with a particular variable over the life of the component. Deviations from expected performance of the measured variable are detected prior to the complete loss of margin. This ensures the reliability of the component over its lifetime.

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On August 15, 2016, Sandia hosted a visit by Professor Venkatesh Narayanamurti. Prof Narayanamurti (Benjamin Peirce Research Professor of Technology and Public Policy at Harvard, Board Member of the Belfer Center for Science and International Affairs, former Dean of the School of Engineering and Applied Science at Harvard, former Dean of Engineering at UC Santa Barbara, and former Vice President of Division 1000 at Sandia). During the visit, a small, informal, all-day idea exploration session on "Towards an Engineering and Applied Science of Research" was conducted. This document is a brief synopsis or "footprint" of the presentations and discussions at this Idea Exploration Session. The intent of this document is to stimulate further discussion about pathways Sandia can take to improve its Research practices.

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This report documents tests conducted by Sandia National Laboratories (SNL) on behalf of the U.S. Department of State to evaluate a temporary anti-personnel (TAP) barrier system developed by Mitigation Technologies. For this, the SNL Denial and Structural Assessment department developed a test protocol for the evaluation of the TAP barrier system on the basis of deployment efficiency and barrier effectiveness against a riotous/mob attack threat. The test protocol was then executed by SNL personnel and the results of the testing are documented.

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A finite element numerical analysis model has been constructed that consists of a realistic mesh capturing the geometries of Bayou Choctaw (BC) Strategic Petroleum Reserve (SPR) site and multi - mechanism deformation ( M - D ) salt constitutive model using the daily data of actual wellhead pressure and oil - brine interface. The salt creep rate is not uniform in the salt dome, and the creep test data for BC salt is limited. Therefore, the model calibration is necessary to simulate the geomechanical behavior of the salt dome. The cavern volumetric closures of SPR caverns calculated from CAVEMAN are used for the field baseline measurement. The structure factor, A 2 , and transient strain limit factor, K 0 , in the M - D constitutive model are used for the calibration. The A 2 value obtained experimentally from the BC salt and K 0 value of Waste Isolation Pilot Plant (WIPP) salt are used for the baseline values. T o adjust the magnitude of A 2 and K 0 , multiplication factors A2F and K0F are defined, respectively. The A2F and K0F values of the salt dome and salt drawdown skins surrounding each SPR cavern have been determined through a number of back fitting analyses. The cavern volumetric closures calculated from this model correspond to the predictions from CAVEMAN for six SPR caverns. Therefore, this model is able to predict past and future geomechanical behaviors of the salt dome, caverns, caprock , and interbed layers. The geological concerns issued in the BC site will be explained from this model in a follow - up report .

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Subsidence monitoring is a critical component to understanding the cavern integrity of salt storage caverns. This report looks at historical and recent data from two of the three West Hackberry dome cavern operators. DOE SPR and LA Storage are coordinating subsidence surveys to create a comprehensive understanding of ground movement above the dome. Data from annual level and rod surveys, GPS, and tiltmeter data show the sites are experiencing typical ground movement. The highest subsidence rate is seen in the middle of the DOE SPR site at just under one inch per year with less ground movement around the edge of the site. A GPS and tiltmeter instrument in the northeast areas of the DOE SPR site has not seen any trend change since the devices were installed in 2013. Comparison between recent ground movement data and historical trends suggest that there is no reason to believe that any DOE SPR or LA Storage caverns have been structurally compromised.

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This monthly report is intended to communicate the status of North Slope ARM facilities managed by Sandia National Labs.

Si-MOS based QD qubits are attractive due to their similarity to the current semiconductor industry. We introduce a highly tunable MOS foundry compatible qubit design that couples an electrostatic quantum dot (QD) with an implanted donor. We show for the first time coherent two-axis control of a two-electron spin logical qubit that evolves under the QD-donor exchange interaction and the hyperfine interaction with the donor nucleus. The two interactions are tuned electrically with surface gate voltages to provide control of both qubit axes. Qubit decoherence is influenced by charge noise, which is of similar strength as epitaxial systems like GaAs and Si/SiGe.

The near-term objective of the EC team is to establish an operating, commercially scalable Recompression Closed Brayton Cycle (RCBC) to be constructed for the NE - STEP demonstration system (demo) with the lowest risk possible. A systems engineering approach is recommended to ensure adequate requirements gathering, documentation, and mode ling that supports technology development relevant to advanced reactors while supporting crosscut interests in potential applications. A holistic systems engineering model was designed for the ART Energy Conversion program by leveraging Concurrent Engineering, Balance Model, Simplified V Model, and Project Management principles. The resulting model supports the identification and validation of lifecycle Brayton systems requirements, and allows designers to detail system-specific components relevant to the current stage in the lifecycle, while maintaining a holistic view of all system elements.

Soldering technology has made tremendous strides in the past half-century. Whether structural or electronic, all solder joints must provide a level of reliability that is required by the application. This Part 1 report examines the effects of filler metal properties and soldering process on joint reliability. Solder alloy composition must have the appropriate melting and mechanical properties that suit the product's assembly process(es) and use environment. The filler metal must also optimize solderability (wetting-and-spreading) to realize the proper joint geometry. Here, the soldering process also affects joint reliability. The choice of flux and thermal profile support the solderability performance of the molten filler metal to successfully fill the gap and complete the fillet.

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This report describes the use of cloud computing services for running complex public domain performance assessment problems. The work consisted of two phases: Phase 1 was to demonstrate complex codes, on several differently configured servers, could run and compute trivial small scale problems in a commercial cloud infrastructure. Phase 2 focused on proving non-trivial large scale problems could be computed in the commercial cloud environment. The cloud computing effort was successfully applied using codes of interest to the geohydrology and nuclear waste disposal modeling community.

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The overall goal of this project is to establish a network of TCUs with essential advanced manufacturing (AM) facilities, associated training and education programs, and private sector and federal agency partnerships to both prepare an American Indian AM workforce and create economic and employment opportunities within Tribal communities through design, manufacturing, and marketing of high quality products. Some examples of high quality products involve next generation grid components such as mechanical energy storage, cabling for distribution of energy, and electrochemical energy storage enclosures. Sandia National Laboratories (Sandia) is tasked to provide technical advising, planning, and academic program development support for the TCU/American Indian Higher Education Consortium (AIHEC) Advanced Manufacturing Project. The TCUs include Bay Mills Community College (BMCC), Cankdeska Cikana Community College (CCCC), Navajo Technical University (NTU), Southwestern Indian Polytechnic Institute (SIPI), and Salish Kooteani College. AIHEC and Sandia, with collaboration from SIPI, will be establishing an 8-week summer institute on the SIPI campus during the summer of 2017. Up to 20 students from TCUs are anticipated to take part in the summer program. The goal of the program is to bring AM science, technology, engineering, and mathematics (STEM) awareness and opportunities for the American Indian students. Prior to the summer institute, Sandia will be providing reviews on curriculum plans at the each of the TCUs to ensure the content is consistent with current AM design and engineering practice. In addition, Sandia will provide technical assistance to each of the TCUs in regards to their current AM activities.

Physical property measurements including viscosity, density, thermal conductivity, and heat capacity of low-molecular weight polydimethylsiloxane (PDMS) fluids were measured over a wide temperature range (-50°C to 150°C when possible). Properties of blends of 1 cSt and 20 cSt PDMS fluids were also investigated. Uncertainties in the measurements are cited. These measurements will provide greater fidelity predictions of environmental sensing device behavior in hot and cold environments.

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The 2017 Annual Terrestrial Sampling Plan for Sandia National Laboratories/New Mexico on Kirtland Air Force Base has been prepared in accordance with the “Letter of Agreement Between Department of Energy, National Nuclear Security Administration, Sandia Field Office (DOE/NNSA/SFO) and 377th Air Base Wing (ABW), Kirtland Air Force Base (KAFB) for Terrestrial Sampling” (signed January 2017), Sandia National Laboratories, New Mexico (SNL/NM). The Letter of Agreement requires submittal of an annual terrestrial sampling plan.

This report describes findings from the culminating experiment of the LDRD project entitled, "Analyst-to-Analyst Variability in Simulation-Based Prediction". For this experiment, volunteer participants solving a given test problem in engineering and statistics were interviewed at different points in their solution process. These interviews are used to trace differing solutions to differing solution processes, and differing processes to differences in reasoning, assumptions, and judgments. The issue that the experiment was designed to illuminate -- our paucity of understanding of the ways in which humans themselves have an impact on predictions derived from complex computational simulations -- is a challenging and open one. Although solution of the test problem by analyst participants in this experiment has taken much more time than originally anticipated, and is continuing past the end of this LDRD, this project has provided a rare opportunity to explore analyst-to-analyst variability in significant depth, from which we derive evidence-based insights to guide further explorations in this important area.

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This goal of this project is to address the current inability to assess the overall error and uncertainty of data products developed and distributed by DOE’s Consequence Management (CM) Program. This is a widely recognized shortfall, the resolution of which would provide a great deal of value and defensibility to the analysis results, data products, and the decision making process that follows this work. A global approach to this problem is necessary because multiple sources of error and uncertainty contribute to the ultimate production of CM data products. Therefore, this project will require collaboration with subject matter experts across a wide range of FRMAC skill sets in order to quantify the types of uncertainty that each area of the CM process might contain and to understand how variations in these uncertainty sources contribute to the aggregated uncertainty present in CM data products. The ultimate goal of this project is to quantify the confidence level of CM products to ensure that appropriate public and worker protections decisions are supported by defensible analysis.

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Solving sparse linear systems from the discretization of elliptic partial differential equations (PDEs) is an important building block in many engineering applications. Sparse direct solvers can solve general linear systems, but are usually slower and use much more memory than effective iterative solvers. To overcome these two disadvantages, a hierarchical solver (LoRaSp) based on H2-matrices was introduced in [22]. Here, we have developed a parallel version of the algorithm in LoRaSp to solve large sparse matrices on distributed memory machines. On a single processor, the factorization time of our parallel solver scales almost linearly with the problem size for three-dimensional problems, as opposed to the quadratic scalability of many existing sparse direct solvers. Moreover, our solver leads to almost constant numbers of iterations, when used as a preconditioner for Poisson problems. On more than one processor, our algorithm has significant speedups compared to sequential runs. With this parallel algorithm, we are able to solve large problems much faster than many existing packages as demonstrated by the numerical experiments.

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This paper presents a 3D finite element model for simulating shear slip on fractures in rock in response to coupled thermo-poro-mechanical processes. The modeling is part of a broader effort to investigate the role of pore pressure and cooling by cold water injection on shear slip and permeability increase in granitic rock using laboratory shearing experiments under triaxial conditions. In particular, 3D thermo-poro-mechanical finite element modeling and analysis of injection experiment in fractured rock has been carried out to analyze the role of pore pressure, temperature, fracture deformation and their interactions. 4-noded tetrahedral elements are employed for intact rock deformation and transport processes within the matrix. To represent the mechanical response of a fracture surface, zero thickness contact interface element is developed based on recently developed element partitioning algorithm and procedures for applying hydraulic pressure on the fracture surfaces. A Mohr-Coulomb type criterion is adapted to capture the slip on the fracture and to quantify its reversible and irreversible deformation. The numerical model has been calibrated using results from well controlled, advanced laboratory experiments. Excellent agreement between modeling and experimental observations is achieved. Simulation results illustrate that pore pressure increase and rock matrix/fracture surface cooling cause the fracture system to deform and slip. Fracture slip is promoted due to its normal stress reduction associated with cooling effect of cold fluid injection. The numerical model provides a physics-based understanding of the role of coupled processes on shear stimulation phenomenon and the resulting permeability enhancement.

Room-temperature (RT) multiferroics, possessing ferroelectricity and ferromagnetism simultaneously at RT, hold great promise in miniaturized devices including sensors, actuators, transducers, and multi-state memories. In this work, we report a novel 2D layered RT multiferroic system with self-assembled layered supercell structure consisting of two mismatch-layered sub-lattices of [Bi₃O_3+δ] and [MO₂]_1.84 (M=Al/Mn, simply named as BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made of a three-layer-thick Bi-O slab and a one-layer-thick Al/Mn-O octahedra slab along the out-of-plane direction. Strong room-temperature multiferroic responses, e.g., ferromagnetic and ferroelectric properties, have been demonstrated and attributed to the highly anisotropic 2D nature of the non-ferromagnetic and ferromagnetic sublattices which are highly mismatched. The work demonstrates an alternative design approach for new 2D layered oxide materials that hold promises as single-phase multiferroics, 2D oxides with tunable bandgaps, and beyond.

The ability to measure the velocity of neutral atoms and molecules with a precision of several meter/sec provides an opportunity to measure subtle perturbations on electronic states with high resolution. Using Velocity Mapped Ion Imaging we are able to measure induced perturbations of electronic states such as broadening and magnetic and electric field splittings . We demonstrate this ability utilizing the 5s[3/2]₂ → 5p[5/2]₃ cycling transition at 811.5 nm in metastable Kr atoms to investigate the saturation broadening caused by Rabi cycling on a resonant transition with MHz resolution. In addition we investigate the lifetime broadening associated with ionization from the cycling states and the Zeeman splitting of the states. We discuss the inherent limits to resolution obtained with this technique.

This work was conducted as part of a Harry S. Truman Fellowship Laboratory Directed Research and Development project. The goal was to use machine learning methods to provide uncertainty quantification and model improvements for Reynolds Averaged Navier Stokes (RANS) turbulence models. For applications of interest in energy, safety, and security, it is critical to be able to model turbulence accurately. Current RANS models are unreliable for many flows of engineering relevance. Machine learning provides an avenue for developing improved models based on the data generated by high fidelity simulations. In this project, machine learning methods were used to predict when current RANS models would fail. They were also used to develop improved RANS closure models. A key aim was developing a tight feedback loop between scientific domain knowledge and data driven methods. To this end, a methodology for incorporating known invariance constraints into the machine learning models was proposed and evaluated. This work demonstrated that incorporating known constraints into the data driven models provided improved performance and reduced computational cost. This research represents one of the first applications of deep learning to turbulence modeling.

The Nuclear Regulatory Commission's (NRC) current fire protection regulatory framework was initiated in response to a cable fire that occurred at the Browns Ferry Nuclear Power Station in 1975. Following the issuance of several guidance documents, in 1981 the Commission codified deterministic requirements to provide reasonable assurance that fire would not jeopardize reactor safety (10 CFR 50.48 "Fire Protection" and Appendix R to 10 CFR 50). Since then, the results of plant operating experience, NRC inspection activities and cable fire testing programs have served to clarify the application of these requirements. In 2004, the NRC amended 10 CFR Part 50.48 to add a new subsection, 10 CFR 50.48(c), that endorses, with exceptions, the National Fire Protection Association's 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants — 2001 Edition," as a voluntary alternative for demonstrating compliance with Appendix R. To date, approximately half of all operating plants have transitioned to a risk-informed approach under 10 CFR 50.48(c). Regardless of the selected approach, each operating nuclear power plant should establish a comprehensive fire protection program that includes features needed to minimize the likelihood and consequence of firesl. To achieve this objective, fire protection programs integrate the NRC's long-held safety concept of defense-in-depth (DID) by providing multiple barriers against potentially unacceptable consequences of fire. To minimize the frequency and size of fires, the first lines of defense include controls for fire prevention, such as controlling combustibles and ignition sources and fire mitigation features, such as fire detection and suppression systems. In the unlikely event that a fire should start and continue to grow in spite of these features, appropriate fire protection features, such as fire-rated barriers are provided as necessary to ensure the accomplishment of essential shutdown functions. This handbook was specifically developed for NRC inspectors that may be assigned to perform elements of Inspection Procedure (IP) 71111.05T, "Fire Protection (Triennial)," including, (a) "Protection of Safe Shutdown Capabilities," (e) "Alternative Shutdown Capability," and (f) "Circuit Analyses." Thus, the document concentrates solely on the final element of defense-in-depth— ensuring reactor safety will not be compromised in the event of a serious fire. In addition to describing how the NRC's regulatory framework has evolved since the Browns Ferry Fire, the handbook illustrates the content and scope of various analyses typically referenced in a plant's fire protection licensing basis and includes techniques and insights for assessing the plant's conformance to those criteria.

Recent Magnetized Liner Inertial Fusion experiments at the Sandia National Laboratories Z pulsed power facility have featured a PDV (Photonic Doppler Velocimetry) diagnostic in the final power feed section for measuring load current. In this paper, we report on an anomalous pressure that is detected on this PDV diagnostic very early in time during the current ramp. Early time load currents that are greater than both B-dot upstream current measurements and existing Z machine circuit models by at least 1 MA would be necessary to describe the measured early time velocity of the PDV flyer. This leads us to infer that the pressure producing the early time PDV flyer motion cannot be attributed to the magnetic pressure of the load current but rather to an anomalous pressure. Using the MHD code ALEGRA, we are able to compute a time-dependent anomalous pressure function, which when added to the magnetic pressure of the load current, yields simulated flyer velocities that are in excellent agreement with the PDV measurement. As a result, we also provide plausible explanations for what could be the origin of the anomalous pressure.

SNL’s IDC Reengineering Phase 2 team developed 31 Use Cases (UCs) during the E3 Elaboration Iteration. This document describes the changes made to these UCs after their initial delivery to the IDC in October 2016.

Wrought Al-Ge-Si alloys were designed and produced to ensure dislocation bypass strengthening (“hard pin” precipitates) without significant precipitate cutting/shearing (“soft pin” precipitates). These unusual alloys were processed from the melt, solution heat treated and aged. Aging curves at temperatures of 120, 160, 200 and 240 °C were established and the corresponding precipitate spacings, sizes, and morphologies were measured using TEM. The role of non-shearable precipitates in determining the magnitude of Bauschinger was revealed using large-strain compression/tension tests. The effect of precipitates on the Bauschinger response was stronger than that of grain boundaries, even for these dilute alloys. The Bauschinger effect increases dramatically from the under-aged to the peak aged condition and remains constant or decreases slowly through over-aging. This is consistent with reported behavior for Al-Cu alloys (maximum effect at peak aging) and for other Al alloys (increasing through over-aging) such as Al-Cu-Li, Al 6111, Al 2524, and Al 6013. The Al-Ge-Si alloy response was simulated with three microstructural models, including a novel SD (SuperDislocation) model, to reveal the origins of the Bauschinger effect in dilute precipitation-hardened / bypass alloys. The dominant mechanism is related to the elastic interaction of polarized dislocation arrays (generalized pile-up or bow-out model) at precipitate obstacles. Such effects are ignored in continuum and crystal plasticity models.

This study describes a cyber security research & development (R&D) gap analysis and research plan to address cyber security for industrial control system (ICS) supporting critical energy systems (CES). The Sandia National Laboratories (SNL) team addressed a long-term perspective for the R&D planning and gap analysis. Investment will posture CES for sustained and resilient energy operations well into the future.

Elastomeric materials are used as shock isolation materials in a variety of environments to dampen vibrations and/or absorb energy from external impact to minimize energy transfer between two objects or bodies. Some applications require the shock isolation materials to behave as a low-pass mechanical filter to mitigate the shock/impact at high frequencies but transmit the energy at low frequencies with minimal attenuation. To fulfill this requirement, a shock isolation material needs to be carefully evaluated and selected with proper experimental design, procedures, and analyses. In this study, a Kolsky bar was modified with precompression (up to 15.5 kN) and confinement capabilities to evaluate low-pass shock isolation performance in terms of acceleration attenuation through a variety of elastomers. Also investigated were the effects of preload and specimen geometry on the low-pass shock isolation response.

Dielectric and piezoelectric properties for Zn1-xMgxO (ZMO) thin films are reported as a function of MgO composition up to and including the phase separation region. Zn1-xMgxO (0.25 ≤ x ≤ 0.5) thin films with c-axis textures were deposited by pulsed laser deposition on platinized sapphire substrates. The films were phase pure wurtzite for MgO concentrations up to 40%; above that limit, a second phase with rocksalt structure evolves with strong {100} texture. With increasing MgO concentration, the out-of-plane (d33,f) and in-plane (e31,f) piezoelectric coefficients increase by 360% and 290%, respectively. The increase in piezoelectric coefficients is accompanied by a 35% increase in relative permittivity. Loss tangent values fall monotonically with increasing MgO concentration, reaching a minimum of 0.001 for x ≥ 0.30, at which point the band gap is reported to be 4 eV. The enhanced piezoelectric response, the large band gap, and the low dielectric loss make Zn1-xMgxO an interesting candidate for thin film piezoelectric devices, and demonstrate that compositional phase transformations provide opportunities for property engineering.

The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that the nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities.

We introduce a topology-aware performance optimization and modeling workflow for AMR simulation that includes two new modeling tools, ProgrAMR and Mota Mapper, which interface with the BoxLib AMR framework and the SSTmacro network simulator. ProgrAMR allows us to generate and model the execution of task dependency graphs from high-level specifications of AMR-based applications, which we demonstrate by analyzing two example AMR-based multigrid solvers with varying degrees of asynchrony. Mota Mapper generates multiobjective, network topology-aware box mappings, which we apply to optimize the data layout for the example multigrid solvers. While the sensitivity of these solvers to layout and execution strategy appears to be modest for balanced scenarios, the impact of better mapping algorithms can be significant when performance is highly constrained by network hop latency. Furthermore, we show that network latency in the multigrid bottom solve is the main contributing factor preventing good scaling on exascale-class machines.

This paper details a model for the response of a finite- or an infinite-length wire interacting with a conducting ground to an electromagnetic pulse excitation. We develop a frequency–domain method based on transmission line theory that we name ATLOG–Analytic Transmission Line Over Ground. This method is developed as an alternative to full-wave methods, as it delivers a fast and reliable solution. It allows for the treatment of finite or infinite lossy, coated wires, and lossy grounds. The cases of wire above ground, as well as resting on the ground and buried beneath the ground are treated. The reported method is general and the time response of the induced current is obtained using an inverse Fourier transform of the current in the frequency domain. The focus is on the characteristics and propagation of the transmission line mode. Comparisons with full-wave simulations strengthen the validity of the proposed method.

Here, a new method for the solution of the non-linear equations forming the core of constitutive model integration is proposed. Specifically, the trust-region method that has been developed in the numerical optimization community is successfully modified for use in implicit integration of elastic-plastic models. Although attention here is restricted to these rate-independent formulations, the proposed approach holds substantial promise for adoption with models incorporating complex physics, multiple inelastic mechanisms, and/or multiphysics. As a first step, the non-quadratic Hosford yield surface is used as a representative case to investigate computationally challenging constitutive models. The theory and implementation are presented, discussed, and compared to other common integration schemes. Multiple boundary value problems are studied and used to verify the proposed algorithm and demonstrate the capabilities of this approach over more common methodologies. Robustness and speed are then investigated and compared to existing algorithms. Through these efforts, it is shown that the utilization of a trust-region approach leads to superior performance versus a traditional closest-point projection Newton-Raphson method and comparable speed and robustness to a line search augmented scheme.

Here, a new method for the solution of the non-linear equations forming the core of constitutive model integration is proposed. Specifically, the trust-region method that has been developed in the numerical optimization community is successfully modified for use in implicit integration of elastic-plastic models. Although attention here is restricted to these rate-independent formulations, the proposed approach holds substantial promise for adoption with models incorporating complex physics, multiple inelastic mechanisms, and/or multiphysics. As a first step, the non-quadratic Hosford yield surface is used as a representative case to investigate computationally challenging constitutive models. The theory and implementation are presented, discussed, and compared to other common integration schemes. Multiple boundary value problems are studied and used to verify the proposed algorithm and demonstrate the capabilities of this approach over more common methodologies. Robustness and speed are then investigated and compared to existing algorithms. Through these efforts, it is shown that the utilization of a trust-region approach leads to superior performance versus a traditional closest-point projection Newton-Raphson method and comparable speed and robustness to a line search augmented scheme.

A new method for the solution of the non-linear equations forming the core of constitutive model integration is proposed. Specifically, the trust-region method that has been developed in the numerical optimization community is successfully modified for use in implicit integration of elastic-plastic models. Although attention here is restricted to these rate-independent formulations, the proposed approach holds substantial promise for adoption with models incorporating complex physics, multiple inelastic mechanisms, and/or multiphysics. As a first step, the non-quadratic Hosford yield surface is used as a representative case to investigate computationally challenging constitutive models. The theory and implementation are presented, discussed, and compared to other common integration schemes. Multiple boundary value problems are studied and used to verify the proposed algorithm and demonstrate the capabilities of this approach over more common methodologies. Robustness and speed are then investigated and compared to existing algorithms. As a result through these efforts, it is shown that the utilization of a trust-region approach leads to superior performance versus a traditional closest-point projection Newton-Raphson method and comparable speed and robustness to a line search augmented scheme.

We demonstrate the ultrafast formation of terahertz (THz) metasurfaces through all-optical creation of spatially modulated carrier density profiles in a deep-subwavelength GaAs film. The switch-on of the transient plasmon mode, governed by the GaAs effective electron mass and electron− phonon interactions, is revealed by structured-optical pump THz probe spectroscopy, on a time scale of 500 fs. By modulating the carrier density using different pump fluences, we observe a wide tuning of the electric dipole resonance of the transient GaAs metasurface from 0.5 THz to 1.7 THz. Furthermore, we numerically demonstrate that the metasurface presented here can be generalized to more complex architectures for realizing functionalities such as perfect absorption, leading to a 30 dB modulation depth. The platform also provides a pathway to achieve ultrafast manipulation of infrared beams in the linear and, potentially, nonlinear regime.

The wealth of information available on seemingly every topic creates a considerable challenge both for information providers trying to rise above the noise and discerning individuals trying to find relevant, trustworthy information. We approach this information problem by investigating how passive versus interactive information interventions can impact the antecedents of behavior change using the context of solar energy adoption, where persistent information gaps are known to reduce market potential. We use two experiments to investigate the impact of both passive and interactive approaches to information delivery on the antecedents (attitudes, subjective norms, and perceived behavioral control in the Theory of Planned Behavior) of intentions and behavior, as well as their effect on intentions and behavior directly. The passive information randomized control trial delivered via Amazon Mechanical Turk tests the effectiveness of delivering the same content in a single message versus multiple shorter messages. The interactive information delivery uses an online (mobile and PC) trivia-style gamification platform. Both experiments use the same content and are carried out over a two-week time period. Lastly, our findings suggest that interactive, gamified information has greater impact than passive information, and that shorter multiple messages of passive information are more effective than a single passive message.

An important question in the reading literature regards the nature of the semantic information readers can extract from the parafovea (i.e., the next word in a sentence). Recent eye-tracking findings have found a semantic parafoveal preview benefit under many circumstances, and findings from event-related brain potentials (ERPs) also suggest that readers can at least detect semantic anomalies parafoveally. We use ERPs to ask whether fine-grained aspects of semantic expectancy can affect the N400 elicited by a word appearing in the parafovea. In an RSVP-with-flankers paradigm, sentences were presented word by word, flanked 2° bilaterally by the previous and upcoming words. Stimuli consisted of high constraint sentences that were identical up to the target word, which could be expected, unexpected but plausible, or anomalous, as well as low constraint sentences that were always completed with the most expected ending. Findings revealed an N400 effect to the target word when it appeared in the parafovea, which was graded with respect to the target’s expectancy and congruency within the sentence context. Moreover, when targets appeared at central fixation, this graded congruency effect was mitigated, suggesting that the semantic information gleaned from parafoveal vision functionally changes the semantic processing of those words when foveated.

Advances in the emerging field of coherent quantum feedback control (CQFC) have led to the development of new capabilities in the areas of quantum control and quantum engineering, with a particular impact on the theory and applications of quantum optical networks. For this study, we consider a CQFC network consisting of two coupled optical parametric oscillators (OPOs) and study the squeezing spectrum of its output field. The performance of this network as a squeezed-light source with desired spectral characteristics is optimized by searching over the space of model parameters with experimentally motivated bounds. We use the QNET package to model the network’s dynamics and the PyGMO package of global optimization algorithms to maximize the degree of squeezing at a selected sideband frequency or the average degree of squeezing over a selected bandwidth. The use of global search methods is critical for identifying the best possible performance of the CQFC network, especially for squeezing at higher-frequency sidebands and higher bandwidths. The results demonstrate that the CQFC network of two coupled OPOs makes it possible to vary the squeezing spectrum, effectively utilize the available pump power, and overall significantly outperform a single OPO. Additionally, the Hessian eigenvalue analysis shows that the squeezing generation performance of the optimally operated CQFC network is robust to small variations of phase parameters.

Hexanitrostilbene (HNS) films were deposited onto polycarbonate substrates using vacuum thermal sublimation. The deposition conditions were varied in order to alter porosity in the films, and the resulting microstructures were quantified by analyzing ion-polished cross-sections using scanning electron microscopy. The effects of these changes in microstructure on detonation velocity and the critical thickness needed to sustain detonation were determined. The polycarbonate substrates also acted as recording plates for detonation experiments, and films near the critical thickness displayed distinct patterns in the dent tracks that indicate instabilities in the detonation front when approaching failure conditions.

We report a series of time-resolved spectroscopic measurements that aim to characterize the reactions that occur during shock initiation of high explosives. The experiments employ time-and wavelength-resolved emission spectroscopy to analyze light emitted from detonating thin explosive films. This paper presents analysis of optical emission spectra from hexanitrostilbene (HNS) and pentaerythritol tetranitrate (PETN) thin film samples. Both vibrationally resolved and broadband emission features are observed in the spectra and area as electronic transitions of intermediate species.

Physical vapor deposition is a technique that can be used to produce explosive films with controlled geometry and microstructure. Films of the high explosive hexanitroazobenzene (HNAB) were deposited by vacuum thermal evaporation. HNAB deposits in an amorphous state that crystallizes over time into a polycrystalline material with high density and a consistent porosity distribution. In previous work, we evaluated detonation critical thickness in HNAB films in an effectively infinite slab geometry with insignificant side losses. In this work, the effect of geometry on detonation failure was investigated by performing experiments on films with different thicknesses, while also changing lateral dimensions such that side losses became significant. The experimental failure thickness was determined to be 75.5 μm and 71.6 μm, for 400 μm and 1600 μm wide HNAB lines, respectively. It follows from this that the minimum width to achieve detonation behavior representing an infinite slab configuration is greater than 400 μm.

Understanding the mechanisms by which shock waves initiate chemical reactions in explosives is key to understanding their unique and defining property: the ability to undergo rapid explosive decomposition in response to mechanical stimulus. Although shock-induced reactions in explosives have been studied experimentally and computationally for decades, the nature of even the first chemical reactions that occur in response to shock remain elusive. To predictively understand how explosives respond to shock, the detailed sequence of events that occurs-mechanical deformation, energy transfer, bond breakage, and first chemical reactions-must be understood at the quantum-mechanical level. This paper reviews recent work in this field and ongoing experimental and theoretical work at Sandia National Laboratories in this important area of explosive science.

A multi-point microwave interferometer (MPMI) concept is presented for non-invasively monitoring the internal transit of a shock, detonation, or reaction front in energetic media. The concept utilizes an electro-optic (EO) crystal to impart a timevarying phase lag onto a laser with a microwave signal. Polarization optics convert this phase lag into an amplitude modulation. A heterodyne interferometer compares the modulated laser beam to a constant reference. This enables the detection of changes in the modulating microwave frequency generated by the motion of the measurement surface. The design is scalable and makes use of the established construction and analysis methods employed in photonic Doppler velocimetry (PDV). The technical challenges associated with the concept are the frequency stability of the lasers, the amount of light return after EO modulation, and the frequency uncertainty of fast Fourier transform (FFT) methods.

Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a more broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.

Dynamic materials experiments on the Z-machine are beginning to reach a regime where traditional analysis techniques break down. Time dependent phenomena such as strength and phase transition kinetics often make the data obtained in these experiments difficult to interpret. We present an inverse analysis methodology to infer the equation of state (EOS) from velocimetry data in these types of experiments, building on recent advances in the propagation of uncertain EOS information through a hydrocode simulation. An example is given for a shock-ramp experiment in which tantalum was shock compressed to 40 GPa followed by a ramp to 80 GPa. The results are found to be consistent with isothermal compression and Hugoniot data in this regime.

A kinetic description for electronic excitation of helium for principal quantum number n 4 has been included into a particle-in-cell (PIC) simulation utilizing direct simulation Monte Carlo (DSMC) for electron-neutral interactions. The excited electronic levels radiate state-dependent photons with wavelengths from the extreme ultraviolet (EUV) to visible regimes. Photon wavelengths are chosen according to a Voigt distribution accounting for the natural, pressure, and Doppler broadened linewidths. This method allows for reconstruction of the emission spectrum for a non-thermalized electron energy distribution function (EEDF) and investigation of high energy photon effects on surfaces, specifically photoemission. A parallel plate discharge with a fixed field (i.e. space charge neglected) is used to investigate the effects of including photoemission for a Townsend discharge. When operating at a voltage near the self-sustaining discharge threshold, it is observed that the electron current into the anode is higher when including photoemission from the cathode than without even when accounting for self-absorption from ground state atoms. The photocurrent has been observed to account for as much as 20% of the total current from the cathode under steady-state conditions.

The dispersion and connectivity of particles with a high degree of polydispersity is relevant to problems involving composite material properties and reaction decomposition prediction and has been the subject of much study in the literature. This work utilizes Monte Carlo models to predict percolation thresholds for a two-dimensional systems containing disks of two different radii. Monte Carlo simulations and spanning probability are used to extend prior models into regions of higher polydispersity than those previously considered. A correlation to predict the percolation threshold for binary disk systems is proposed based on the extended dataset presented in this work and compared to previously published correlations. A set of boundary conditions necessary for a good fit is presented, and a condition for maximizing percolation threshold for binary disk systems is suggested.

It is therefore of paramount importance to quantify the three dimensional propagation characteristics of infrasound from buried sources. Despite initial success with using an octocopter to quantify ground motion with a seismic hammer (Jones et al., 2015), attempts to capture buried explosion sources using this method have proven very difficult. Even when successful, octocopter-borne sensors suffer from high levels of background noise, have limited flight time due to battery life, and require substantial resources to deploy.

We present a new collection of data on the load-stress relaxation-unload behavior of MinK and FiberFrax Board (FF) insulation materials used as pellets in-line with thermal battery electrochemical stacks. Both materials were subjected to standard thermal preparations, and then tested at room temperature. Intermediate term stress relaxation tests are presented (order 104 minutes of relaxation) showing that FF relaxation is not significantly stress or deformation dependent, but MinK is moderately so. Moreover, stress-strain curves associated with specimen unloading, reloading, and unloading again are presented for both materials. FF and MinK are substantially different here. Acute material variability is observed though test conditions and material preparations are standardized. A modeling approach is presented to empirically estimate the amount of stress relaxation at room temperature, and from this state, represent the unloading stress-strain behavior of both materials. This effort provides a complete framework for representing (in an engineering sense) both materials in thermal battery performance simulations.

Energetic materials (EMs, explosives, pyrotechnics, propellants) provide high-power output of high temperature reaction products. These products can be solid, liquid, or gaseous during reaction or after the products have equilibrated with the surroundings. For example, high explosives typically consist of carbon, hydrogen, nitrogen, and oxygen bonded within a single molecule, and produce almost exclusively gaseous products. Conversely, intermetallics consist of physical mixtures of metals and metalloids, and produce almost exclusively condensed products. Other materials such as pyrotechnics and propellants have intermediate behavior. All energetic materials react in a self-propagating manner that after ignition, does not necessarily require energy input from the surroundings. The range of reaction velocities can range from mm/s for intermetallics, to km/s for high explosives. Energetic material selection depends on numerous requirements specific to the needs of a system. High explosives are used for applications where high pressure gases are necessary for pushing or fracturing materials (e.g., rock, metal) or creating shock waves or air blast. Propellants are used to produce moderate-pressure, high-temperature products without a shock wave. Pyrotechnics are used to produce numerous effects including: high-temperature products, gases, light, smoke, sound, and others. Thermites are used to produce heat, high-temperature products, materials, and other effects that require condensed products. Intermetallics are used to produce high-temperature condensed products and materials, with very little gas production. Numerous categories of energetic materials exist with overlapping definitions, effects, and properties.

This paper investigates three-dimensional cut wire pair (CWP) behavior in vertically oriented meta-atoms. We first analyze CWP metamaterial inclusions using full-wave electromagnetic simulations. The scattering behavior of the vertical CWP differs substantially from that of the planar version of the same structure. In particular, we show that the vertical CWP supports a magnetic resonance that is solely excited by the incident magnetic field. This is in stark contrast to the bianisotropic resonant excitation of in-plane CWPs. We further show that this CWP behavior can occur in other vertical metamaterial resonators, such as back-to-back linear dipoles and back-to-back split ring resonators (SRRs), due to the strong coupling between the closely spaced metallic elements in the back-to-back configuration. In the case of SRRs, the vertical CWP mode (unexplored in previous literature) can be excited with a magnetic field that is parallel to both SRR loops, and exists in addition to the familiar fundamental resonances of the individual SRRs. In order to fully describe the scattering behavior from such dense arrays of three-dimensional structures, coupling effects between the close-packed inclusions must be included. Here, the new flexibility afforded by using vertical resonators allows us to controllably create purely electric inclusions, purely magnetic inclusions, as well as bianisotropic inclusions, and vastly increases the degrees of freedom for the design of metafilms.

Uniaxial strain, plate-on-plate impact experiments were performed on cold-rolled Ni/Al multilayer composites and the resulting Hugoniot was determined through time-resolved measurements combined with impedance matching. The experimental Hugoniot agreed with that previously predicted by two dimensional (2D) meso-scale calculations [Specht et al., J. Appl. Phys. 111, 073527 (2012)]. Additional 2D meso-scale simulations were performed using the same computational method as the prior study to reproduce the experimentally measured free surface velocities and stress profiles. These simulations accurately replicated the experimental profiles, providing additional validation for the previous computational work.

In this work, under-expanded cryogenic hydrogen jets were investigated experimentally for their ignition and flame characteristics. The test facility described herein, was designed and constructed to release hydrogen at a constant temperature and pressure, to study the dispersion and thermo-physical properties of cryogenic hydrogen releases and flames. In this study, a non-intrusive laser spark focused on the jet axis was used to measure the maximum ignition distance. The radiative power emitted by the corresponding jet flames was also measured for a range of release scenarios from 37 K to 295 K, 2–6 barabsthrough nozzles with diameters from 0.75 to 1.25 mm. The maximum ignition distance scales linearly with the effective jet diameter (which scales as the square root of the stagnant fluid density). A 1-dimensional (stream-wise) cryogenic hydrogen release model developed previously at Sandia National Laboratories (although this model is not yet validated for cryogenic hydrogen) was exercised to predict that the mean mole fraction at the maximum ignition distance is approximately 0.14, and is not dependent on the release conditions. The flame length and width were extracted from visible and infra-red flame images for several test cases. The flame length and width both scale as the square root of jet exit Reynolds number, as reported in the literature for flames from atmospheric temperature hydrogen. As shown in previous studies for ignited atmospheric temperature hydrogen, the radiative power from the jet flames of cold hydrogen scales as a logarithmic function of the global flame residence time. The radiative heat flux from jet flames of cold hydrogen is higher than the jet flames of atmospheric temperature hydrogen, for a given mass flow rate, due to the lower choked flow velocity of low-temperature hydrogen. This study provides critical information with regard to the development of models to inform the safety codes and standards of hydrogen infrastructure.

We review liquid hydrogen (LH2) as a maritime vessel fuel, from descriptions of its fundamental properties to its practical application and safety aspects, in the context of the San Francisco Bay Renewable Energy Electric Vessel with Zero Emissions (SF-BREEZE) high-speed fuel-cell ferry. Since marine regulations have been formulated to cover liquid natural gas (LNG) as a primary propulsion fuel, we frame our examination of LH2as a comparison to LNG, for both maritime use in general, and the SF-BREEZE in particular. Due to weaker attractions between molecules, LH2is colder than LNG, and evaporates more easily. We describe the consequences of these physical differences for the size and duration of spills of the two cryogenic fuels. The classical flammability ranges are reviewed, with a focus on how fuel buoyancy modifies these combustion limits. We examine the conditions for direct fuel explosion (detonation) and contrast them with initiation of normal (laminar) combustion. Direct fuel detonation is not a credible accident scenario for the SF-BREEZE. For both fuels, we review experiments and theory elucidating the deflagration to detonation transition (DDT). LH2fires have a shorter duration than energy-equivalent LNG fires, and produce significantly less thermal radiation. The thermal (infrared) radiation from hydrogen fires is also strongly absorbed by humidity in the air. Hydrogen permeability is not a leak issue for practical hydrogen plumbing. We describe the chemistry of hydrogen and methane at iron surfaces, clarifying their impact on steel-based hydrogen storage and transport materials. These physical, chemical and combustion properties are pulled together in a comparison of how a LH2or LNG pool fire on the Top Deck of the SF-BREEZE might influence the structural integrity of the aluminum deck. Neither pool fire scenario leads to net heating of the aluminum decking. Overall, LH2and LNG are very similar in their physical and combustion properties, thereby posing similar safety risks. For ships utilizing LH2or LNG, precautions are needed to avoid fuel leaks, minimize ignition sources, minimize confined spaces, provide ample ventilation for required confined spaces, and to monitor the enclosed spaces to ensure any fuel accumulation is detected far below the fuel/air mix threshold for any type of combustion.

Dissolved CO₂ in the subsurface resulting from geological CO₂ storage may react with minerals in fractured rocks, confined aquifers, or faults, resulting in mineral precipitation and dissolution. The overall rate of reaction can be affected by coupled processes including hydrodynamics, transport, and reactions at the (sub) pore-scale. In this work pore-scale modeling of coupled fluid flow, reactive transport, and heterogeneous reactions at the mineral surface is applied to account for permeability alterations caused by precipitation-induced pore-blocking. This paper is motivated by observations of CO₂ seeps from a natural CO₂ sequestration analog, Crystal Geyser, Utah. Observations along the surface exposure of the Little Grand Wash fault indicate the lateral migration of CO₂ seep sites (i.e., alteration zones) of 10–50 m width with spacing on the order of ~100 m over time. Sandstone permeability in alteration zones is reduced by 3–4 orders of magnitude by carbonate cementation compared to unaltered zones. One granular porous medium and one fracture network systems are used to conceptually represent permeable porous media and locations of conduits controlled by fault-segment intersections and/or topography, respectively. Simulation cases accounted for a range of reaction regimes characterized by the Damköhler (Da) and Peclet (Pe) numbers. Pore-scale simulation results demonstrate that combinations of transport (Pe), geochemical conditions (Da), solution chemistry, and pore and fracture configurations contributed to match key patterns observed in the field of how calcite precipitation alters flow paths by pore plugging. This comparison of simulation results with field observations reveals mechanistic explanations of the lateral migration and enhances our understanding of subsurface processes associated with the CO₂ injection. In addition, permeability and porosity relations are constructed from pore-scale simulations which account for a range of reaction regimes characterized by the Da and Pe numbers. Finally, the functional relationships obtained from pore-scale simulations can be used in a continuum scale model that may account for large-scale phenomena mimicking lateral migration of surface CO₂ seeps.

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. It is shown that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distribution determined by electron microscopy. The electron microscopy images are analyzed using new 2D histograms that correlate major and minor image projections to reveal elongated nanocrystals, a conclusion supported by grazing incidence small-angle X-ray scattering and high-resolution transmission electron microscopy. Finally, the absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.

Low frequency sound waves transmit information on both natural and anthropogenic phenomena, transfer energy between the lower and upper atmosphere, and often propagate for thousands of kilometers. These sound waves are typically in the "infrasound" (below human hearing) range. Although the vast majority of geoacoustic sensor networks have existed on the Earth's surface, microphones drifting in the atmosphere may have much greater sensitivity as well as sample regions inaccessible from the ground.

The resonance modes in Mach 0.94 turbulent flow over a cavity having a length-to-depth ratio of five were explored using time-resolved particle image velocimetry and time-resolved pressure sensitive paint. Mode-switching occurred in the velocity field simultaneous with the pressure field. The first cavity mode corresponded to large-scale motions in shear layer and in the vicinity of the recirculation region, whereas the second and third modes contained organized structures associated with shear layer vortices. Modal surface pressures exhibited streamwise periodicity generated by the interference of downstream-traveling disturbances in shear layer with upstream-traveling acoustical waves. Because of this interference, the modal velocity fields also exhibited local maxima at locations containing pressure minima and vice-versa. Modal convective (phase) velocities, based on cross-correlations of bandpass-filtered velocity fields, decreased with decreasing mode number as the modal activity resided in lower portions of the cavity. These phase velocities also exhibited streamwise periodicity caused by wave interference. The measurements demonstrate that despite the complexities inherent in compressible cavity flows, many of the most prevalent resonance dynamics can be described with simple acoustical analogies.

The k-ε turbulence model has been described as perhaps “the most widely used complete turbulence model.” This family of heuristic Reynolds Averaged Navier-Stokes (RANS) turbulence closures is supported by a suite of model parameters that have been estimated by demanding the satisfaction of well-established canonical flows such as homogeneous shear flow, log-law behavior, etc. While this procedure does yield a set of so-called nominal parameters, it is abundantly clear that they do not provide a universally satisfactory turbulence model that is capable of simulating complex flows. Recent work on the Bayesian calibration of the k-ε model using jet-in-crossflow wind tunnel data has yielded parameter estimates that are far more predictive than nominal parameter values. Here we develop a self-similar asymptotic solution for axisymmetric jet-in-crossflow interactions and derive analytical estimates of the parameters that were inferred using Bayesian calibration. The self-similar method utilizes a near field approach to estimate the turbulence model parameters while retaining the classical far-field scaling to model flow field quantities. Our parameter values are seen to be far more predictive than the nominal values, as checked using RANS simulations and experimental measurements. They are also closer to the Bayesian estimates than the nominal parameters. A traditional simplified jet trajectory model is explicitly related to the turbulence model parameters and is shown to yield good agreement with measurement when utilizing the analytical derived turbulence model coefficients. The close agreement between the turbulence model coefficients obtained via Bayesian calibration and the analytically estimated coefficients derived in this paper is consistent with the contention that the Bayesian calibration approach is firmly rooted in the underlying physical description.

While conducting siderite (FeCO3) solubility experiments in NaCl-Na2CO3 brines, evidence for a second phase was detected. Experiments, in which synthesized siderite was reacted with high ionic strength (0.18 - 7.5 m) solutions at room temperature and high pH (>10), were conducted in a glovebox. As the aging time of siderite-bearing experiments increased, the pH of the solution decreased, signaling formation of a hydroxyl-bearing phase. Decreasing pH values are interpreted to indicate that a hydroxyl-bearing phase, such as chukanovite, is the reaction controlling solid in the solid assemblage. Chukanovite was tentatively identified by XRD analysis. We set out, therefore, to determine the thermodynamic stability of chukanovite under the experimental conditions. Aqueous thermodynamic model parameters were determined with experimentally analyzed Fe(II) solubility data, and subsequently yielded a proposed formation free energy of chukanovite (-1149.8 kJ/mol).

Borate is present in natural groundwaters and borate is also released into groundwaters when borosilicate glass, waste form for high level nuclear waste, is corroded. Borate can form an aqueous complex, AmHB4O7 2+, with actinides in +III oxidation state. In this work, we present our evaluation of the equilibrium constant for formation of AmHB4O7 2+ and the associated Pitzer interaction parameters at 25°C. Using Nd(III) as an analog to Am(III), solubility data of Nd(OH)3(s) in NaCl solutions in the presence of borate ion from the literature, is used to determine Am(III) interactions with borate. The log10K for the formation reaction is 37.34. This evaluation is in accordance with the Waste Isolation Pilot Plant (WIPP) thermodynamic model in which the borate species include B(OH)3(aq), B(OH)4 -, B3O3(OH)4 -, B4O5(OH)4 2-, and NaB(OH)4(aq). The WIPP thermodynamic database uses the Pitzer model to calculate activity coefficients of aqueous species. In addition, the equilibrium constant for dissolution of AmB9O13(OH)4(cr) at 25°C is evaluated from the solubility data on NdB9O13(OH)4(cr) in NaCl solutions, again using Nd(III) as an analog to Am(III). The log10K for the dissolution reaction is -79.30. In the evaluation for log10K for the dissolution reaction, AmHB4O7 2+ is also considered. The equilibrium constant and Pitzer parameters evaluated by this study will be important to describe the chemical behavior of Am(III) in the presence of borate in geological repositories.

Spurious energy in received radar data is unanticipated and undesired signal relevant to radar target signatures, usually a consequence of nonideal component and circuit behavior, perhaps due to I/Q imbalance, nonlinear component behavior, additive interference (e.g. cross-talk, etc.), or other sources. The manifestation of the spurious energy in a range-Doppler map or image can often be influenced by appropriate pulse-to-pulse phase modulation. Comparing multiple images having been processed with the same data but different signal paths and modulations allows identifying undesired spurs and then cropping or apodizing them.

It is often advantageous to modify, or warp, radar waveforms, particularly with respect to group-delay and spectral dilation. These warping adjustments may facilitate real-time motion compensation of waveforms in radar systems, especially when those waveforms are generated by a digital parametric waveform generator. Relevant waveforms to this paper include Frequency Modulated (FM) waveforms, such as the Linear-FM (LFM) chirp, Non-Linear FM (NLFM) chirp, and other general FM waveforms. We present techniques for making fine adjustments to dynamically warp general FM waveforms.

Printed circuit heat exchangers (PCHEs) have an important role in supercritical CO2 (sCO2) Brayton cycles because of their small footprint and the high level of recuperation required for this power cycle. Compact heat exchangers like PCHEs are a rapidly evolving technology, with many companies developing various designs. One technical unknown that is common to all compact heat exchangers is the flow distribution inside the headers that affects channel flow uniformity. For compact heat exchangers, the core frontal area is often large compared with the inlet pipe area, increasing the possibility of flow maldistribution. With the large area difference, there is potential for higher flow near the center and lower flow around the edges of the core. Flow maldistribution increases pressure drop and decreases effectiveness. In some header geometries, flow separation inside the header adds to the pressure drop without increasing heat transfer. This is the first known experiment to test for flow maldistribution by direct velocity measurements in the headers. A PCHE visualization prototype was constructed out of transparent acrylic for optical flow measurements with Particle Image Velocimetry (PIV). The channels were machined out of sheets to form many semi-circular cross sections typical of chemically-etched plates used in PCHE fabrication. These plates were stacked and bolted together to resemble the core geometry. Two header geometries were tested, round and square, both with a normally-oriented jet. PIV allows for velocities to be measured in an entire plane instantly without disturbing the flow. Small particles of approximately 10 micrometers in diameter were added to unheated water. The particles were illuminated by two laser flashes that were carefully timed, and two images were acquired with a specialized digital camera. The movement of particle groups was detected by a cross-correlation algorithm with a result of about 50k velocity measurements in a plane. The velocity distribution inside the header volume was mapped using this method over many planes by traversing the PCHE relative to the optical equipment. The level of flow maldistribution was measured by the spatially-changing velocity coming out of the channels. This effect was quantified by the coefficient of variation proposed by Baek et al. The relative levels of flow maldistribution in the different header geometries in this study were assessed. With highly-resolved velocity measurements, improvements to header geometry to reduce flow maldistribution can be developed.

This paper presents a study of alternative heliostat standby aiming strategies and their impact on avian flux hazards and operational performance of a concentrating solar power plant. A mathematical model was developed that predicts the bird-feather temperature as a function of solar irradiance, thermal emittance, convection, and thermal properties of the feather. The irradiance distribution in the airspace above the Ivanpah Unit 2 heliostat field was simulated using a ray-trace model for two different times of the day, four days of the year, and nine different standby aiming strategies. The impact of the alternative aiming strategies on operational performance was assessed by comparing the heliostat slew times from standby position to the receiver for the different aiming strategies. Increased slew times increased a proxy start-up time that reduced the simulated annual energy production. Results showed that spreading the radial aim points around the receiver to a distance of ∼150 m or greater reduced the hazardous exposure times that the feather temperature exceeded the hazard metric of 160 °C. The hazardous exposure times were reduced by ∼23% and 90% at a radial spread of aim points extending to 150 m and 250 m, respectively, but the simulated annual energy production decreased as a result of increased slew times. Single point-focus aiming strategies were also evaluated, but these strategies increased the exposure hazard relative to other aiming strategies.

The Rim-to-Rim Wearables At The Canyon for Health (R2R WATCH) study examines metrics recordable on commercial off the shelf (COTS) devices that are most relevant and reliable for the earliest possible indication of a health or performance decline. This is accomplished through collaboration between Sandia National Laboratories (SNL) and The University of New Mexico (UNM) where the two organizations team up to collect physiological, cognitive, and biological markers from volunteer hikers who attempt the Rim-to-Rim (R2R) hike at the Grand Canyon. Three forms of data are collected as hikers travel from rim to rim: physiological data through wearable devices, cognitive data through a cognitive task taken every 3 hours, and blood samples obtained before and after completing the hike. Data is collected from both civilian and warfighter hikers. Once the data is obtained, it is analyzed to understand the effectiveness of each COTS device and the validity of the data collected. We also aim to identify which physiological and cognitive phenomena collected by wearable devices are the most relatable to overall health and task performance in extreme environments, and of these ascertain which markers provide the earliest yet reliable indication of health decline. Finally, we analyze the data for significant differences between civilians’ and warfighters’ markers and the relationship to performance. This is a study funded by the Defense Threat Reduction Agency (DTRA, Project CB10359) and the University of New Mexico (The main portion of the R2R WATCH study is funded by DTRA. UNM is currently funding all activities related to bloodwork. DTRA, Project CB10359; SAND2017-1872 C). This paper describes the experimental design and methodology for the first year of the R2R WATCH project.

Dissolved CO2 in the subsurface resulting from geological CO2 storage may react with minerals in fractured rocks, confined aquifers, or faults, resulting in mineral precipitation and dissolution. The overall rate of reaction can be affected by coupled processes including hydrodynamics, transport, and reactions at the (sub) pore-scale. In this work pore-scale modeling of coupled fluid flow, reactive transport, and heterogeneous reactions at the mineral surface is applied to account for permeability alterations caused by precipitation-induced pore-blocking. This work is motivated by observations of CO2 seeps from a natural CO2 sequestration analog, Crystal Geyser, Utah. Observations along the surface exposure of the Little Grand Wash fault indicate the lateral migration of CO2 seep sites (i.e., alteration zones) of 10–50 m width with spacing on the order of ~100 m over time. Sandstone permeability in alteration zones is reduced by 3–4 orders of magnitude by carbonate cementation compared to unaltered zones. One granular porous medium and one fracture network systems are used to conceptually represent permeable porous media and locations of conduits controlled by fault-segment intersections and/or topography, respectively. Simulation cases accounted for a range of reaction regimes characterized by the Damköhler (Da) and Peclet (Pe) numbers. Pore-scale simulation results demonstrate that combinations of transport (Pe), geochemical conditions (Da), solution chemistry, and pore and fracture configurations contributed to match key patterns observed in the field of how calcite precipitation alters flow paths by pore plugging. This comparison of simulation results with field observations reveals mechanistic explanations of the lateral migration and enhances our understanding of subsurface processes associated with the CO2 injection. In addition, permeability and porosity relations are constructed from pore-scale simulations which account for a range of reaction regimes characterized by the Da and Pe numbers. The functional relationships obtained from pore-scale simulations can be used in a continuum scale model that may account for large-scale phenomena mimicking lateral migration of surface CO2 seeps.

Product formation from the low-temperature oxidation of two isotopologues of the proposed biofuel butanone was studied via multiplexed photoionization mass spectrometry (MPIMS) at 500 and 700 K to elucidate product branching ratios for R and QOOH pathways. Products were identified and branching ratios quantified for a number of species, with the aid of ab initio calculations. Chain-inhibiting C-C β-scission of R and select chain-propagating channels are discussed. Whilst methyl vinyl ketone and HOO, (from chain-inhibiting pathways) were found to be major products, chain propagation pathways leading to carbonyl and cyclic ether species following OH-elimination from QOOH were found to be pertinent at both temperatures. At 700 K, R C-C β-scission was significantly enhanced, as evident in the branching ratios, however the formation of QOOH-derived chain-propagation products remained relevant.

High-voltage (20 kV peak), single-pulse, nanosecond, low-temperature plasma discharges were examined in nitrogen-diluted desiccated air (15.9% oxygen) with addition of 1%, 2%, and 3% carbon dioxide or water for a pin-to-pin electrode configuration in an optically accessible spark calorimeter at elevated density (2.9 kg/m3). Discharge behavior was characterized through pressure-rise calorimetry, direct imaging of excited-state atomic oxygen, and high-speed schlieren. Increasing carbon dioxide or water concentration led to an increased likelihood of surface discharges rather than the desired streamer discharge between the pin electrodes. For streamer discharges, carbon dioxide addition decreased the electrical-to-thermal conversion efficiency, while minimal impact was observed for water. Both carbon dioxide and water addition led to faster pressure rise rates. Carbon dioxide addition decreased excited state atomic oxygen signal, while water addition led to negligible changes. Finally, increased streamer branching was observed in the schlieren images when carbon dioxide or water was added to the gas mixture.

When exposed to a strong radiant heat source (>1,000 kW/m2), combustible materials pyrolyze and ignite under certain conditions. Studies of this nature are scarce, yet important for some applications. Pyrolysis models derived at lower flux conditions do not necessarily extrapolate well to high-heat-flux conditions. The material response is determined by a complex interplay of thermal and chemical transport phenomena, which are often difficult to model. To obtain model validation data at high-heat-flux conditions (up to 2500 kW/m2), experiments on a variety of organic and engineered materials were performed at the National Solar Thermal Test Facility at Sandia National Laboratories. Mass loss during the short duration (2-4 sec) heat pulse was determined using the pre- and post-test weight. The mass-loss data were fairly linear in the fluence range of 200-6000 kJ/m2. When divided into subsets based on material types, the mass loss was similar at the peak flux/fluence condition for engineered polymers (≈1 g) and organic materials (≈2.5 g), although some exceptions exist (PMMA, dry pine needles). Statistical correlations were generated and used to evaluate the significance of the observed trends. These results contribute to the validation data for simulating fires and ignition resulting from very high incident heat flux.

A human readiness levels (HRL) scale provides a framework to factor in the human dimension during technology development. This framework promotes careful consideration of the human as a part of the system throughout the product lifecycle. Insufficient attention to the human component of the system can lead to added costs, delayed deliverables, system failure, and even the loss of human life in high-consequence systems. We make the economic and technical justification for using an HRL scale by evaluating a reactive case study within a national laboratory. We create a historical technology readiness level (TRL) adoption roadmap to forecast a potential HRL adoption roadmap. We identify characteristics of organizations that are most likely to adopt the scale and conclude by recommending several project management tactics to ensure successful implementation.

The flame structure corresponding to lean hydrogen–air premixed flames in intense sheared turbulence in the thin reaction zone regime is quantified from flame thickness and conditional scalar dissipation rate statistics, obtained from recent direct numerical simulation data of premixed temporally-evolving turbulent slot jet flames [1]. It is found that, on average, these sheared turbulent flames are thinner than their corresponding planar laminar flames. Extensive analysis is performed to identify the reason for this counter-intuitive thinning effect. The factors controlling the flame thickness are analyzed through two different routes i.e., the kinematic route, and the transport and chemical kinetics route. The kinematic route is examined by comparing the statistics of the normal strain rate due to fluid motion with the statistics of the normal strain rate due to varying flame displacement speed or self-propagation. It is found that while the fluid normal straining is positive and tends to separate iso-scalar surfaces, the dominating normal strain rate due to self-propagation is negative and tends to bring the iso-scalar surfaces closer resulting in overall thinning of the flame. The transport and chemical kinetics route is examined by studying the non-unity Lewis number effect on the premixed flames. The effects from the kinematic route are found to couple with the transport and chemical kinetics route. In addition, the intermittency of the conditional scalar dissipation rate is also examined. It is found to exhibit a unique non-monotonicity of the exponent of the stretched exponential function, conventionally used to describe probability density function tails of such variables. The non-monotonicity is attributed to the detailed chemical structure of hydrogen-air flames in which heat release occurs close to the unburnt reactants at near free-stream temperatures.

In the present work, a direct numerical simulation (DNS) of an experimental high Karlovitz number (Ka) CH4/air piloted premixed flame was analyzed to study the inner structure and the stabilization mechanism of the turbulent flame. A reduced chemical mechanism for premixed CH4/air combustion with NOx based on GRI-Mech3.0 was used, including 268 elementary reactions and 28 transported species. The evolution of the stretch factor, I0, indicates that the burning rate per unit flame surface area is considerably reduced in the near field and exhibits a minimum at x/D = 8. Downstream, the burning rate gradually increases. The stretch factor is different between different species, suggesting the quenching of some reactions but not others. Comparison between the turbulent flame and strained laminar flames indicates that certain aspects of the mean flame structure can be represented surprisingly well by flamelets if changes in boundary conditions are accounted for and the strain rate of the mean flow is employed; however, the thickening of the flame due to turbulence is not captured. The spatial development of displacement speeds is studied at higher Ka than previous DNS. In contrast to almost all previous studies, the mean displacement speed conditioned on the flame front is negative in the near field, and the dominant contribution to the displacement speed is normal diffusion with the reaction contribution being secondary. Further downstream, reaction overtakes normal diffusion, contributing to a positive displacement speed. The negative displacement speed in the near field implies that the flame front situates itself in the pilot region where the inner structure of the turbulent flame is affected significantly, and the flame stabilizes in balance with the inward flow. Notably, in the upstream region of the turbulent flame, the main reaction contributing to the production of OH, H+O2⇔O+OH (R35), is weak. Moreover, oxidation reactions, H2+OH⇔H+H2O (R79) and CO+OH⇔CO2+H (R94), are influenced by H2O and CO2 from the pilot and are completely quenched. Hence, the entire radical pool of OH, H and O is affected. However, the fuel consumption layer remains comparably active and generates heat, mainly via the reaction CH4+OH⇔CH3+H2O (R93).

Controlling the distribution of structural defects in nanostructures is important since such defects can strongly affect critical properties, including thermal and electronic transport. However, characterizing the defect arrangements in individual nanostructures is difficult because of the small length scales involved. Here, we investigate the evolution of microstructural disorder with annealing in electrochemically deposited Bi2Te3 nanowires, which are of interest for thermoelectrics. We combine Convergent Beam Electron Diffraction (CBED) and Scanning Transmission Electron Microscopy (STEM) to provide the necessary spatial and orientational resolution. We find that despite their large initial grain sizes and strong 1120 crystallographic texturing, the as-deposited nanowires still exhibit significant intragranular orientational disorder. Annealing drives both grain growth and a significant reduction in the intragranular disorder. The results are discussed in the context of the existing understanding of the initial microstructure of electrodeposited materials and the understanding of annealing microstructures in both electrochemically deposited and bulk-deformed materials. This analysis highlights the importance of assessing both the grain size and intragranular disorder in understanding the microstructural evolution of individual nanostructures.

Coupled reservoir and geomechanical simulations are significantly important to understand the long-term behavior of geologic carbon storage (GCS) systems. In this study, we performed coupled fluid flow and geomechanical modeling of CO2 storage using available field data to (1) validate our existing numerical model and (2) perform parameter estimation via inverse modeling to identify the impact of key geomechanical (Young's modulus and Biot's coefficient) and hydrogeological (permeability and anisotropy ratio) properties on surface uplift and the pore pressure buildup at In Salah in Algeria. Two sets of surface uplift data featuring low and high uplifts above two injection wells and the maximum change in the pore pressure due to CO2 injection were used to constrain the inverse model. Forward simulation results with representative parameter values from the literature match both low and high surface uplifts reasonably well and predicted the maximum change in the pore pressure. In particular, forward modeling results with estimated Biot's coefficients for reservoir and caprock layers, match the observed uplift well, highlighting the significance of Biot's coefficient in coupled reservoir and geomechanical models. Parameter estimation with 12 parameter sets for both low and high uplift data demonstrates that multiple sets of parameters can match the observed data equally well and the inclusion of the pore pressure data is critically important to constrain the parameter solution during inverse modeling. For a majority of cases, estimation results for both low and high uplift data show the vertical intrinsic permeability and Young's modulus of the reservoir remained close to 13 mD (1.3×10−14 m2) and 10 GPa, respectively, suggesting that these parameters may represent the actual effective properties. Additionally, higher correlations between reservoir permeability and caprock's Biot's coefficient with high surface uplift data were observed consistently under the pore pressure constraint, suggesting the inclusion of the pore pressure constraint is required to estimate the proper values of coupled flow and geomechanical properties associated with different surface uplift data. Overall, this study suggests that given limited data, including Biot's coefficient, in addition to permeability and Young's modulus can enhance parameter estimation of the geomechanical response during GCS.

In this paper, we will summarize a group of architectural principles that inform the development of secure control system architectures, followed by a methodology that allows designers to understand the attack surface of components and subsystems in a way that supports the integration of these surfaces into a single attack surface. We will then show how this methodology can be used to analyze the control system attack surface from a variety of threats, including knowledgeable insiders. We close the paper with an overview of how this approach can be folded into a more rigorous mathematical analysis of the system to define the system's security posture.

A new multi-step, solution-phase method for the spontaneous deposition of tungsten from a room temperature ethereal solution is reported. This immersion process relies on the deposition of a sacrificial zinc coating which is galvanically displaced by the ethermediated reduction of oxophilic WCl6. Subsequent thermal treatment renders a crystalline, metallic tungsten film. The chemical evolution of the surface and formation of a complex intermediate tungsten species is characterized by X-ray diffraction, infrared spectroscopy, and X-ray photoelectron spectroscopy. Efficient metallic tungsten deposition is first characterized on a graphite substrate and then demonstrated on a functional carbon foam electrode. The resulting electrochemical performance of the modified electrode is interrogated with the canonical aqueous ferricyanide system. A tungsten-coated carbon foam electrode showed that both electrode resistance and overall electrochemical cell resistance were reduced by 50%, resulting in a concomitant decrease in redox peak separation from 1.902 V to 0.783 V. This process promises voltage efficiency gains in electrodes for energy storage technologies and demonstrates the viability of a new route to tungsten coating for technologies and industries where high conductivity and chemical stability are paramount.

This paper presents a risk assessment of a Liquefied Natural Gas (LNG)/diesel hybrid locomotive to identify and rank failures that could result in the release of LNG or Gaseous Natural Gas (GNG) to the surrounding environment. The Federal Railroad Administration (FRA) will analyze industry safety assessments of the proposed rail vehicles and the goal of this risk analysis is to identify and prioritize hazard scenarios so the FRA can ensure that they are properly addressed. For operational activities, a Failure Modes and Effects Analysis (FMEA) was performed to identify high risk failure modes. A modified hazard and operability study (HAZOP) methodology was used to analyze hazard scenarios for the maintenance activities for the LNG and Compressed Natural Gas (CNG) dual-fuel locomotives and the LNG tender car. Because refueling operations are highly dependent on human interactions, a human factors assessment was also performed on a sample refueling procedure to identify areas of improvement and identify best practices for analyzing future procedures. The FMEA resulted in the identification of 87 total failure modes for the operational phase, three of which were deemed to have a High risk priority, all involving the cryogenic storage tank. The HAZOP for the LNG tender resulted in the identification of eight credible hazard scenarios and the HAZOP for the locomotive in the maintenance mode identified 27 credible hazard scenarios. The high and medium risk failure modes and hazard scenarios should be prioritized for further analysis.

The Deep Borehole Field Test (DBFT) is a planned multi-year project led by the US Department of Energy's Office of Nuclear Energy to drill two boreholes to 5 km total depth into crystalline basement in the continental US. The purpose of the first characterization borehole is to demonstrate the ability to characterize in situ formation fluids through sampling and perform downhole hydraulic testing to demonstrate groundwater from 3 to 5 km depth is old and isolated from the atmosphere. The purpose of the second larger-diameter borehole is to demonstrate safe surface and downhole handling procedures. This paper details many of the drilling, testing, and characterization activities planned in the first smaller-diameter characterization borehole.

We present a series of benchmark flames consisting of six partially-premixed piloted dimethyl ether (DME)/air jet flames. These flames provide an opportunity to understand turbulence-flame interactions for oxygenated fuels and to develop predictive models for these interactions using a canonical burner geometry. The development of accurate models for DME/air flames would establish a foundation for studies of more complex oxygenated fuels. The flames are stabilized on a piloted jet burner similar to that of the partially-premixed methane/air jet flames that have been studied extensively within the context of the TNF Workshop. This series of six jet flames spans jet exit Reynolds numbers, ReD, from 29,300 to 73,300 and stoichiometric mixture fractions, ξst, from 0.35 to 0.60. Flame conditions range from very low probability of localized extinction to a high probability of localized extinction and subsequent re-ignition. Measurements in the flames are compared at downstream locations from 5 to 25 diameters above the nozzle exit. Mean and fluctuating velocity components are measured using stereo particle image velocimetry (SPIV). Simultaneous laser-induced fluorescence (LIF) imaging of OH and CH2O provides insights into the distribution of these intermediate species in partially-premixed DME/air flames. OH LIF imaging is also combined with SPIV to investigate the strain rate field across the reaction zone.

For many aerospace applications, there exists significant demand for more accurate tur- bulence models. Data-driven machine learning algorithms have the capability to accurately predict when Reynolds Averaged Navier Stokes (RANS) models will have increased model form uncertainty due to the breakdown of underlying model assumptions. These machine learning models can be used to adaptively trigger relevant model corrections in the regions they are needed. This paper presents a framework for data-driven adaptive physics model- ing that leverages known RANS model corrections and proven machine learning methods. This adaptive physics modeling framework is evaluated for two case studies: fully developed turbulent square duct flow and flow over a wavy wall. It is demonstrated that implement- ing model corrections zonally based on machine learning classification of where underlying RANS model assumptions are violated can achieve the same accuracy as implementing those corrections globally.

The Deep Borehole Field Test will include demonstration of the emplacement and retrieval of test waste packages (containing no waste) in a 5 km deep borehole drilled into the crystalline basement. A conceptual design for packaging, surface handling and transfer equipment, and borehole emplacement was developed in anticipation of the demonstration project. Test packages are designed to withstand external pressure greater than 65 MPa, at temperature up to 170°C. Two packaging concepts were developed: 1) flasktype for granular waste, and 2) internal semi-flush type for waste that is pre-canistered in cylindrical containers. Oilfield casing materials and sealing connections would be selected giving a safety factor of 2.0 against yield. Packages would have threaded fittings top and bottom for attachment of impact limiters and latch fittings. Packages would be lowered one-at-a-time into the borehole on electric wireline. This offers important safety advantages over using drill pipe or coiled tubing to lower waste packages, because it avoids the possibility of dropping a heavy assembly in the borehole. An electromechanical latch would release each package, or reconnect for retrieval. Frequency of waste package delivery to a disposal site could be the effective limit on emplacement throughput. Packages would be delivered in a shielded Type B transportation cask and transferred to a shielded, doubleended transfer cask on site. The transfer cask would be upended over the borehole and secured to the wellhead. The transfer cask would become an integral part of the pressure control envelope for well pressure control. Blowout preventers can be incorporated as needed for regulatory compliance. Operational safety has been assessed with respect to normal operations, and off-normal events that could cause package breach in the borehole. Worker exposures can be limited by using standard industry practices for nuclear material handling. The waste packages would effectively be robust pressure vessels that will not breach if dropped during surface handling. The possibility of package breach in the borehole during emplacement can be effectively eliminated using impact limiters on every package.

We propose here a novel device, called the Triassico, to microscopically study the entire surface of millimeter-sized spheres. The sphere dimensions can be as small as 1 mm, and the upper limit defined only by the power and by the mechanical characteristics of the motors used. Three motorized driving rods are arranged so an equilateral triangle is formed by the rod's axes, on such a triangle the sphere sits. Movement is achieved by rotating the rods with precise relative speeds and by exploiting the friction between the sphere and the rods surfaces. The sphere can be held in place by gravity or by an opposing trio of rods. By rotating the rods with specific relative angular velocities, a net torque can be exerted on the sphere which then rotates. No repositioning of the sphere or of the motors is needed to cover the full surface with the investigating tools. An algorithm was developed to position the sphere at any arbitrary polar and azimuthal angle. The algorithm minimizes the number of rotations needed by the rods, in order to efficiently select a particular position on the sphere surface. A prototype Triassico was developed for the National Ignition Facility, of the Lawrence Livermore National Laboratory (Livermore, California, USA), as a sphere manipulation apparatus for ion microbeam analysis at Sandia National Laboratories (Albuquerque, NM, USA) of Xe-doped DT inertial confinement fusion fuel spheres. Other applications span from samples orientation, ball bearing manufacturing, or jewelry.

An important feature required in all geological disposal system modeling is proper representation of waste package degradation and waste form dissolution. These processes are often treated as batch operations, meaning they are zero-dimensional. However, waste package canister degradation or waste form dissolution are affected by near-field conditions, and thus they must be coupled to the computational domain through the exchange of information on local conditions. Accurate waste package and waste form degradation behavior is essential because processes occurring at the batch level also affect far field conditions through heat and mass transport by advection or diffusion. Presented here is the development and performance of the Waste Form Process Model, an integrated module for waste package canister degradation and waste form dissolution developed by Sandia National Laboratories within PFLOTRAN. PFLOTRAN is an open source, massively parallel subsurface simulator for multiphase, multicomponent, and multiscale reactive flow and transport processes in porous media. PFLOTRAN is used to model geologic disposal systems for the Spent Fuel and Waste Science and Technology (SFWST) Campaign under the Spent Fuel and Waste Disposition Program of the U.S. Department of Energy (DOE) Office of Nuclear Energy.

A series of tests on NAS1352-06-6P threaded fasteners were coupled with analysis to fit constitutive models, evaluate multiple modeling approaches, and ultimately predict failure. Experiments loading the fasteners in tension at both quasistatic and dynamic loading rates were performed to obtain calibration and validation data for the analysis. The fastener was modeled with two low-fidelity approaches - a "plug" of hex elements retaining the nominal fastener geometry (without threads) and a "spot weld", which incorporates similar geometry but the fastener is sliced near its mid-plane to define a tensile loaddisplacement relationship between the two exposed surfaces - to accommodate the use of these modeling methods in a larger, more detailed finite element analysis. Both modeling approaches were calibrated using quasistatic test data and then extended to the dynamic analyses to compare with the analogous test results. The analysis accurately reproduces most acceleration time-histories observed in the dynamic testing but under predicts failure, indicating the possible presence of strain rate effects that have been neglected in the constitutive models.

Parabolic dish technology, for concentrating solar power (CSP) applications, has been continuously modified and improved since the pioneering work in the 1970s. Best practice dishes now have features such as lightweight structure, balanced design, high-quality, low-cost mirror panels, and can be deployed rapidly with little in-field labour. This review focuses on the evolution of dish design, by examining features such as mode of tracking, structure and mirror design, for a wide selection of CSP dish examples. The review includes a brief summary of power generation options – both on-dish and central plant – as well as a discussion about options for storage and hybridisation.

Time multiplexed spectral images of burning aluminum particles from two experiments using a hyperspectral imaging system (HIS) coupled to a high speed video (HSV) camera were investigated. The first experiment looks at ignited aluminum particles generated by a welding torch that were continuously funneled into the imaging plane of the HISHSV system. The HIS was set to hop between two wavelengths at a rate of 300 frames per second (fps): 485.7 nm, the peak emission of aluminum monoxide, and 502.3nm, the bottom of the same emission peak. The second experiment images ignited AlO from the burn of an aluminized ammonium perchlorate solid propellant hoping between the wavelength of 486.3nm and 480.0nm at 2100 fps.

This paper discusses software design choices made during the ongoing development of PFLOTRAN with the intent of improving the longevity and flexibility of the code while maintaining robustness. PFLOTRAN is a massively parallel reactive multiphase flow and transport code employed to simulate subsurface processes in support of radioactive waste management licensing and performance assessment studies. PFLOTRAN's open source licensing, software configuration management, object-oriented design through modern Fortran 2003/2008, approach to coupling scientific process models, and automated testing are discussed in detail.

The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy geological repository for the permanent disposal of defense-related transuranic (TRU) waste. Industrial-grade MgO consisting mainly of the mineral periclase is the only engineered barrier certified by U.S. EPA for emplacement in the WIPP in the U.S. An Mg(OH)2-based engineered barrier consisting mainly of the mineral brucite is to be employed in the Asse repository in Germany. The WIPP is located in a bedded salt formation, and the Asse repository is located in a domal salt formation. Colloids would facilitate transport of contaminants including actinides. The regulator for the WIPP, U.S. Environmental Protection Agency (EPA), expressed its interest that possible formation of mineral colloids by MgO and its hydration and carbonation products under the WIPP-relevant conditions be evaluated. In this presentation, we report a systematic experimental study to address U.S. EPA's interest. We evaluated the possible formation of mineral colloids by using two approaches. In the first approach, as the hydration products, Mg(OH)2 (brucite), and(Mg)3Cl(OH)5′4H2O (phase 5), and the carbonation product, (Mg)5(CO3)4(OH)2•4H2O (hydromagnesite), contain magnesium, should mineral fragment colloids exist, magnesium concentrations in solution samples from MgO hydration and carbonation experiments would show a dependence on ultrafiltration, i.e., a decrease in magnesium concentrations as a function of ultrafiltration with decreasing molecular weight (MW) cut-offs. Therefore, we investigated magnesium concentrations from solutions samples in hydration and carbonation experiments as a function of ultrafiltration. We ultrafiltered solutions with a series of MW cut-off filters at 100 κD, 50 κD, 30 κD and 10 κD. Our results demonstrate that the magnesium concentrations remain constant with decreasing MW cut-offs, implying the absence of mineral fragment colloids. In the second approach, because Cs+ is easily absorbed by colloids, we spiked MgO hydration and carbonation experiments under the WIPP-relevant conditions with Cs+. Then, we ultra-filtered solutions with a series of MW cut-off filters at 100 κD, 50 κD, 30 κD and 10 κD. The concentrations of Cs do not change as a function of MW cut-offs, indicating the absence of colloids from MgO hydration and carbonation products. Therefore, both approaches demonstrate that the absence of mineral fragment colloids from MgO hydration and carbonation products.

As unmanned systems (UMS) proliferate for security and defense applications, autonomous control system capabilities that enable them to perform tactical operations are of increasing interest. These operations, in which UMS must match or exceed the performance and speed of people or manned assets, even in the presence of dynamic mission objectives and unpredictable adversary behavior, are well beyond the capability of even the most advanced control systems demonstrated to date. In this paper we deconstruct the tactical autonomy problem, identify the key technical challenges, and place them into context with the autonomy taxonomy produced by the US Department of Defense's Autonomy Community of Interest. We argue that two key capabilities beyond the state of the art are required to enable an initial fieldable capability: rapid abstract perception in appropriate environments, and tactical reasoning. We summarize our work to date in tactical reasoning, and present initial results from a new research program focused on abstract perception in tactical environments. This approach seeks to apply semantic labels to a broad set of objects via three core thrusts. First, we use physics-based multi-sensor fusion to enable generalization from imperfect and limited training data. Second, we pursue methods to optimize sensor perspective to improve object segmentation, mapping and, ultimately, classification. Finally, we assess the potential impact of using sensors that have not traditionally been used by UMS to perceive their environment, for example hyperspectral imagers, on the ability to identify objects. Our technical approach and initial results are presented.