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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Assembly and testing of a large zoom lens for proton radiography

A zoom lens has been designed for proton radiography applications. Radiographic images are recorded at the end of an accelerator, where protons exit an aluminum vacuum window, producing a shadowgraph image onto an LYSO (lutetium yttrium orthosilicate) scintillator. Emission from this 5-inch-square scintillator reflects off a pellicle and is then collected by a zoom lens located 24 inches away. Proton radiography can make high-speed, multi-frame radiographs or radiographic movies. This zoom lens provides 2X magnification for viewing different object sizes. The zoom lens incorporates eleven lenses, including a moving doublet that changes the magnification. Refocus of the camera is required when zooming. Only one moving doublet lens is required to change magnification. The stop was anchored to the moving doublet, and its diameter is unchanged throughout magnification changes. The entire lens system is housed in a cylindrical tube. This lens will be used with a 10-frame camera with a 44 × 44 mm square image format and 1100 × 1100 pixel resolution. Suppressing stray light is very important in this lens system. Radial compensation is controlled by two locking micrometers on element 9, which relaxes the mechanical tolerancing. A helical cam barrel using a linear rail controls the movement of the doublet. Alignment of the mechanical gears will be discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Prototype design and experimental tests of a zoom mirror system for the APS upgrade

Mirror-based zoom optics systems can offer variable focal spot sizes over a wide range, which is essential for coherent nanoprobe beamlines, such as the proposed Atomic beamline in the Advanced Photon Source (APS) upgrade project. The success of the zoom mirror system in the nano-focusing regime requires the development of high-precision deformable mirrors, in-situ surface profilers and wavefront sensors, and advanced feedback control system. A prototype 1-D zoom mirror system consists of two vertical focusing mirrors was designed, assembled, and tested at the APS 1-BM beamline. The system consists of a bender-based mirror with a capacitive-sensorarray-based real-time mirror profiler, a bimorph adaptive mirror, and a grating interferometer for the wavefront monitoring. In this work, we present the design and test results of the prototype system demonstrating its zoom focusing capability.

adaptive optics↗
DOE OSTI2022

Real-time streaming tomographic reconstruction with on-demand data capturing and 3D zooming to regions of interest

Complex dynamic tomographic experiments at brilliant X-ray light sources require real-time feedback on the sample changes with respect to environmental conditions, selecting representative regions of interest for high-resolution scanning, and on-demand data saving mechanisms for storing only relevant projections acquired by fast area detectors and reducing data volumes. Here the implementation details of a 3D real-time imaging monitoring instrument, with zooming to a volume of interest with easy-to-use visualization via ImageJ , a tool familiar to most beamline users, is presented. The instrument relies on optimized data flow between the detector and processing machines and is implemented on commodity computers. The instrument has been developed at beamline 2-BM of the Advanced Photon Source, where the automatic lens changing mechanism for zooming is implemented with an Optique Peter microscope. Performance tests demonstrate the ability to process more than 3 GB of projection data per second and generate real-time 3D zooming with different magnification. These new capabilities are essential for new APS Upgrade instruments such as the projection microscope under development at beamline 32-ID. The efficacy of the proposed instrument was demonstrated during an in situ tomographic experiment on ice and gas hydrate formation in porous samples.

3D zooming↗
DOE OSTI2021

The AGORA High-resolution Galaxy Simulations Comparison Project. III. Cosmological Zoom-in Simulation of a Milky Way–mass Halo

In this work, we present a suite of high-resolution cosmological zoom-in simulations to z = 4 of a 10 12 M⊙ halo at z = 0, obtained using seven contemporary astrophysical simulation codes (Art-I, Enzo, Ramses, Changa, Gadget-3, Gear, and Gizmo) widely used in the numerical galaxy formation community. The physics prescriptions for gas cooling and heating and star formation are the same as the ones used in our previous Assembling Galaxies of Resolved Anatomy (AGORA) disk comparison but now account for the effects of cosmological processes such as the expansion of the universe, intergalactic gas inflow, and the cosmic ultraviolet background radiation emitted by massive stars and quasars. In this work, we introduce the most careful comparison yet of galaxy formation simulations run by different code groups, together with a series of four calibration steps each of which is designed to reduce the number of tunable simulation parameters adopted in the final run. In the first two steps, we methodically calibrate the gas physics, such as cooling and heating, in simulations without star formation. In the third step, we seek agreement on the total stellar mass produced with the common star formation prescription used in the AGORA disk comparison, in stellar-feedback-free simulations. In the last calibration step, we activate stellar feedback, where each code group is asked to set the feedback prescription to as close to the most widely used one in its code community as possible, while aiming for convergence in the stellar mass at z = 4 to the values predicted by semiempirical models. After all the participating code groups successfully complete the calibration steps, we achieve a suite of cosmological simulations with similar mass assembly histories down to z = 4. With numerical accuracy that resolves the internal structure of a target halo (≲100 physical pc at z = 4), we find that the codes overall agree well with one another, e.g., in gas and stellar properties, but also show differences, e.g., in circumgalactic medium (CGM) properties. We argue that, if adequately tested in accordance with our proposed calibration steps and common parameters, high-resolution cosmological zoom-in simulations can have robust and reproducible results. New code groups are invited to join and enrich this comparison by generating equivalent models or to test the code's compatibility on their own, by adopting the common initial conditions, the common easy-to-implement physics package, and the proposed calibration steps. Further analyses of the zoom-in simulations presented here will be presented in forthcoming reports from the AGORA Collaboration, including studies of the CGM, simulations by additional codes, and results at lower redshift.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

RAZAR Adaptive Zoom Rifle Scope

RAZAR adaptive zoom is a revolutionary method whereby true optical zoom is accomplished by cooperatively varying the focal lengths of multiple active optical elements in the system.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2016

Cygnus Zoom Lens Autofocus Capability

Presentation describes work on the Cygnus zoom lens autofocus, to include gimbal mount redesign, autofocus program development, camera tip/tilt and focus program development, and the zoom lens system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Zoomed high-resolution simulations of Multi-coupled Dark Energy: cored galaxy density profiles at high redshift

We perform for the first time high-resolution zoom-in re-simulations of individual halos in the context of the Multi-coupled Dark Energy (McDE) scenario, which is characterised by the existence of two distinct Dark Matter particle species with opposite couplings to a Dark Energy scalar field. We compare the structural properties of the simulated halos to the standard ΛCDM results. The zoomed-in initial conditions are set up using a specifically designed code called ZInCo that we publicly release along with the present paper. Our numerical results allow to investigate in detail and with unprecedented resolution the halo segregation process that characterises McDE cosmologies from its very early stages. In particular, we find that in contrast to what could be inferred from previous numerical analysis at lower resolution, the segregation process is already in place at redshifts as high as z ∼ 7. Most remarkably, we find that the subsequent evolution of the segregation leads to the formation of cored total matter density profiles with a core size that progressively increases in time. The shape of the cored profiles can be accurately predicted as the superposition of two NFW profiles with an increasing offset, thereby confirming the interpretation of the simulations results in terms of the segregation of the two dark matter components of the halo as a consequence of their different coupling to the Dark Energy field.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

UniverseMachine: Predicting Galaxy Star Formation over Seven Decades of Halo Mass with Zoom-in Simulations

In this work, we apply the empirical galaxy–halo connection model UniverseMachine to dark-matter-only zoom-in simulations of isolated Milky Way (MW)–mass halos, along with their parent cosmological simulations. This application extends UniverseMachine predictions into the ultrafaint dwarf galaxy regime (10 2 M ⊙ ≤ M * ≤ 10 5 M ⊙) and yields a well-resolved stellar mass–halo mass (SMHM) relation over the peak halo mass range of 10 8 –10 15 M ⊙. The extensive dynamic range provided by the zoom-in simulations allows us to assess specific aspects of dwarf galaxy evolution predicted by UniverseMachine. In particular, although UniverseMachine is not constrained for dwarf galaxies with M * ≲ 10 8 M ⊙, our predicted SMHM relation is consistent with that inferred for MW satellite galaxies at z = 0 using abundance matching. However, UniverseMachine predicts that nearly all galaxies are actively star-forming below M * ~ 10 7 M ⊙ and that these systems typically form more than half of their stars at z ≲ 4, which is discrepant with the star formation histories of Local Group dwarf galaxies that favor early quenching.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Fast Bayesian optimization of Needle-in-a-Haystack problems using zooming memory-based initialization (ZoMBI)

Abstract Needle-in-a-Haystack problems exist across a wide range of applications including rare disease prediction, ecological resource management, fraud detection, and material property optimization. A Needle-in-a-Haystack problem arises when there is an extreme imbalance of optimum conditions relative to the size of the dataset. However, current state-of-the-art optimization algorithms are not designed with the capabilities to find solutions to these challenging multidimensional Needle-in-a-Haystack problems, resulting in slow convergence or pigeonholing into a local minimum. In this paper, we present a Zooming Memory-Based Initialization algorithm, entitled ZoMBI, that builds on conventional Bayesian optimization principles to quickly and efficiently optimize Needle-in-a-Haystack problems in both less time and fewer experiments. The ZoMBI algorithm demonstrates compute time speed-ups of 400× compared to traditional Bayesian optimization as well as efficiently discovering optima in under 100 experiments that are up to 3× more highly optimized than those discovered by similar methods.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Understanding multi-scale battery degradation with a macro-to-nano zoom through its hierarchy

Lithium-ion batteries (LIBs) feature structural and chemical complexities across a broad range of length scales. It is the hierarchy of the battery structure that determines its functionality. An in-depth understanding of the battery function, degradation, and failure mechanisms requires a thorough and systematic investigation from structural, chemical, mechanical, and dynamic perspectives. Here we present a macro-to-nano zoom through the hierarchy of a commercial 18650 type LIB using a suite of state-of-the-art X-ray microscopy techniques. Damage, deformation, and heterogeneity at different length scales are visualized and are associated with different degradation phenomena and mechanisms. Our results highlight the importance of the mechanical properties of the cathode material, which could impact both the immediate and the long-term cell behaviors significantly. While this study focuses on a commercial lithium cell with a standard configuration, our findings can be extrapolated and are applicable to the development of next-generation energy storage technology, e.g. solid-state batteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Cosmological zoom simulations of z = 2 galaxies: The impact of galactic outflows

We use high-resolution cosmological zoom simulations with ∼200 pc resolution at z = 2 and various prescriptions for galactic outflows in order to explore the impact of winds on the morphological, dynamical, and structural properties of eight individual galaxies with halo masses ∼10{sup 11}-2 × 10{sup 12} M {sub ☉} at z = 2. We present a detailed comparison to spatially and spectrally resolved Hα and other observations of z ≈ 2 galaxies. We find that simulations without winds produce massive, compact galaxies with low gas fractions, super-solar metallicities, high bulge fractions, and much of the star formation concentrated within the inner kiloparsec. Strong winds are required to maintain high gas fractions, redistribute star-forming gas over larger scales, and increase the velocity dispersion of simulated galaxies, more in agreement with the large, extended, turbulent disks typical of high-redshift star-forming galaxies. Winds also suppress early star formation to produce high-redshift cosmic star formation efficiencies in better agreement with observations. Sizes, rotation velocities, and velocity dispersions all scale with stellar mass in accord with observations. Our simulations produce a diversity of morphological characteristics—among our three most massive galaxies, we find a quiescent grand-design spiral, a very compact star-forming galaxy, and a clumpy disk undergoing a minor merger; the clumps are evident in Hα but not in the stars. Rotation curves are generally slowly rising, particularly when calculated using azimuthal velocities rather than enclosed mass. Our results are broadly resolution-converged. These results show that cosmological simulations including outflows can produce disk galaxies similar to those observed during the peak epoch of cosmic galaxy growth.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Quantum adiabatic machine learning by zooming into a region of the energy surface

Recent work has shown that quantum annealing for machine learning, referred to as QAML, can perform comparably to state-of-the-art machine learning methods with a specific application to Higgs boson classification. Here, we propose QAML-Z, an algorithm that iteratively zooms in on a region of the energy surface by mapping the problem to a continuous space and sequentially applying quantum annealing to an augmented set of weak classifiers. Results on a programmable quantum annealer show that QAML-Z matches classical deep neural network performance at small training set sizes and reduces the performance margin between QAML and classical deep neural networks by almost 50% at large training set sizes, as measured by area under the receiver operating characteristic curve. The significant improvement of quantum annealing algorithms for machine learning and the use of a discrete quantum algorithm on a continuous optimization problem both opens a class of problems that can be solved by quantum annealers and suggests the approach in performance of near-term quantum machine learning towards classical benchmarks.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

A Zoom-in Analysis of I/O Logs to Detect Root Causes of I/O Performance Bottlenecks

Scientific applications frequently spend a large fraction of their execution time in reading and writing data on parallel file systems. Identifying these I/O performance bottlenecks and attributing root causes are critical steps toward devising optimization strategies. Several existing studies analyze I/O logs of a set of benchmarks or applications that were run with controlled behaviors. However, there is still a lack of general approach that systematically identifies I/O performance bottlenecks for applications running "in the wild" on production systems. In this study, we have developed an analysis approach of "zooming in" from platform-wide to application-wide to job-level I/O logs for identifying I/O bottlenecks in arbitrary scientific applications. We analyze the logs collected on a Cray XC40 system in production over a two-month period. This study results in several insights for application developers to use in optimizing I/O behavior.

Wang, Teng↗
DOE OSTI2018

Applications of SHARP Toolkit to SFR Challenging Problems: Evaluation of Hot Channel Factors and Demonstration of Zooming Capability

The Simulation-based High-efficiency Advanced Reactor Prototyping (SHARP) toolkit is under development by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign of the U.S. Department of Energy, Office of Nuclear Energy. Beginning in FY17, the NEAMS Campaign initiated the “Sodium-Cooled Fast Reactor (SFR) Challenge Problems” task to apply its advanced modeling and simulation capabilities to important SFR applications. The scope of work includes two major items: the assessment of hot channel factors (HCFs) and the demonstration of a local refinement “zooming” capability, both using the SHARP toolkit. Resolving these challenge problems with the SHARP toolkit can significantly improve the economic competitiveness of an SFR as well as make the tools more accessible for full core confirmatory calculations.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗