Search NASA⌕ Search

SEARCH · Search NASA

Results for “integrators”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

An Ultrathin Single Crystalline Relaxor Ferroelectric Integrated on a High Mobility Semiconductor

The epitaxial growth of multifunctional oxides on semiconductors has opened a pathway to introduce new functionalities to semiconductor device technologies. In particular, ferroelectric materials integrated on semiconductors could lead to low-power field-effect devices that can be used for logic or memory. Essential to realizing such field-effect devices is the development of ferroelectric metal-oxide-semiconductor (MOS) capacitors, in which the polarization of a ferroelectric gate is coupled to the surface potential of a semiconducting channel. Here we demonstrate that ferroelectric MOS capacitors can be realized using single crystalline SrZr x Ti 1-x O 3 (x= 0.7) that has been epitaxially grown on Ge. We find that the ferroelectric properties of SrZr x Ti 1-x O 3 are exceptionally robust, as gate layers as thin as 5 nm give rise to hysteretic capacitance-voltage characteristics that are 2 V in width. The development of ferroelectric MOS capacitors with gate thicknesses that are technologically relevant opens a pathway to realize scalable ferroelectric field-effect devices.

Moghadam, Reza M.↗
DOE OSTI2012

Modeling energy in an Integrated Pollutant Removal (IPR) system with CO{sub 2} capture integrated with oxy-fuel combustion

Oxy-coal combustion is one of the technical solutions for mitigating CO{sub 2} in thermal power plants. Many processes have been evolved in past the decade to capture CO{sub 2} from process industries. Researchers at the National Energy Technology Laboratory (NETL) have patented a process, integrated pollutant removal (IPR), that uses off the shelf technology to produce a sequestration-ready CO{sub 2} stream from an oxy-combustion power plant. The IPR process as it is realized at the Jupiter Oxygen Burner Test Facility is a spray tower (direct-contact heat exchanger) followed by four stages of compression with intercooling. To study the energy flows of the oxy-combustion process, a 15 MW{sub t}h oxy-combustion pulverized-coal-fired plant integrated with the IPR system was simulated and analyzed using ASPEN Plus and ASPEN energy analyzer. This paper discusses flue-gas recycle, energy flow, recovery, and optimization of IPR systems. ASPEN models of heat- and mass-transfer processes in aflue-gas-condensing heat-exchanger system were developed to predict the heat transferred from flue gas to cooling water. The flue-gas exit temperature, cooling water outlet temperature, and energy flows of IPR streams were computed using ASPEN models. Pinch principles are deployed for targeting design and operation-guiding purposes and balancing the heat and mass transfer in the IPR system. The results are expected to support sophistication of the IPR system design, improving its application in a variety of settings. They open the door for valuable IPR efficiency improvements and generalization of methodology for simultaneous management of energy resources.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2011

Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

Previous experiments at the Rifle, Colorado Integrated Field Research Challenge (IFRC) site demonstrated that field-scale addition of acetate to groundwater reduced the ambient soluble uranium concentration. In this report, sediment samples collected before and after acetate field addition were used to assess the active microbes via {sup 13}C acetate stable isotope probing on 3 phases [coarse sand, fines (8-approximately 150 {micro}m), groundwater (0.2-8 {micro}m)] over a 24-day time frame. TRFLP results generally indicated a stronger signal in {sup 13}C-DNA in the 'fines' fraction compared to the sand and groundwater. Before the field-scale acetate addition, a Geobacter-like group primarily synthesized {sup 13}C-DNA in the groundwater phase, an alpha Proteobacterium primarily grew on the fines/sands, and an Acinetobacter sp. and Decholoromonas-like OTU utilized much of the {sup 13}C acetate in both groundwater and particle-associated phases. At the termination of the field-scale acetate addition, the Geobacter-like species was active on the solid phases rather than the groundwater, while the other bacterial groups had very reduced newly synthesized DNA signal. These findings will help to delineate the acetate utilization patterns of bacteria in the field and can lead to improved methods for stimulating distinct microbial populations in situ.

15 GEOTHERMAL ENERGY↗
DOE OSTI2019

Delineating Facies Spatial Distribution by Integrating Ensemble Data Assimilation and Indicator Geostatistics with Level-Set Transformation

The facies-based approach has been widely adopted to delineate an aquifer into distinct geological units with unique distributions of hydraulic, physical, and/or chemical properties. The recent development in ensemble-based data assimilation methods allows both the direct and indirect data to be used to improve facies delineation. A major difficulty in those applications is to honor the spatial continuity and avoid overfitting after data assimilation. We introduce a new facies delineation framework to integrate ensemble data assimilation with traditional transition probability-based geostatistics. A level-set concept is used to parametrize discrete facies indicators and for updating facies shape. During the iterative data assimilation process, we impose spatial continuity by conditioning facies field generation on points selected adaptively based on their sensitivity to observation data. This reconditioning step is a key step to maintain spatial continuity and overcome over-fitting problems in inversion. We selected two examples to evaluate the performance of the new framework in estimating facies-based permeability field. The first example is a two-dimensional synthetic system with transient head data induced by pumping tests used for delineating two facies. The second example is a three-dimensional case with three facies, conceptualized from a field tracer experiment within the Columbia River corridor in Washington State, USA. Both examples demonstrate that the new method can adequately capture the spatial pattern of hydrofacies with reconditioning, which leads to the improved prediction of system behaviors.

Song, Xuehang↗
DOE OSTI2020

Initial Land Use/Cover Distribution Substantially Affects Global Carbon and Local Temperature Projections in the Integrated Earth System Model

Initial land cover distribution varies among Earth system models, an uncertainty in initial conditions that can substantially affect carbon and climate projections. We use the integrated Earth System Model to show that a 3.9 M km2 difference in 2005 global forest area (9–14% of total forest area) generates uncertainties in initial atmospheric CO2 concentration, terrestrial carbon, and local temperature that propagate through a future simulation following the Representative Concentration Pathway 4.5. By 2095, the initial 6 ppmv uncertainty range increases to 9 ppmv and the initial 26 PgC uncertainty range in terrestrial carbon increases to 33 PgC. The initial uncertainty range in annual average local temperature of -0.74 to 0.96 °C persists throughout the future simulation, with a seasonal maximum in Dec-Jan-Feb. These results highlight the importance of accurately characterizing historical land use and land cover to reduce overall initial condition uncertainty.

Di Vittorio, Alan↗
DOE OSTI2020

Integrative Quantitative-Phase and Airy Light-Sheet Imaging

Light-sheet microscopy enables considerable speed and phototoxicity gains, while quantitative-phase imaging confers label-free organelle recognition and metabolic information that are inaccessible by conventional methods. We report the fusion of these two modalities onto a standard inverted microscope that retains compatibility with microfluidics. We describe the utilization of an accelerating Airy-beam light-sheet yielding identical imaging areas with interferometry, and an application in unmasking the effects of cellular noise on metabolic compartmentalization.

Biological sciences, Biological techniques, Micros↗
DOE OSTI2011

An integrated portable Raman sensor with nanofabricated gold bowtie array substrates for energetics detection

An integrated field-portable surface enhaned Raman scattering (SERS) sensing system has been developed and evaluated for quantitative analysis of energetics such as perchlorate (ClO4-) and trinitrotoluene (TNT) at environmentally-relevant concentrations and conditions. The detection system consists of a portable Raman spectrometer equipped with an optical fiber probe that is coupled with novel elevated gold bowtie nanostructural arrays as a sensitive and reproducible SERS substrate. Using the standard addition technique, we show that ClO4- and TNT can be quantified at concentrations as low as 0.66 mg/L (or ~6.6 M) and 0.20 mg/L (~0.9 M), respectively, in groundwater samples collected from selected military sites. This research represents the first step toward the development of a field SERS sensor which may permit rapid, in-situ screening and analysis for various applications including national security, chemical, biological and environmental detection.

Abu Hatab, Nahla A↗
DOE OSTI2024

Integrating the PanDA Workload Management System with the Vera C. Rubin Observatory

The Vera C. Rubin Observatory will produce an unprecedented astronomical data set for studies of the deep and dynamic universe. Its Legacy Survey of Space and Time (LSST) will image the entire southern sky every three to four days and produce tens of petabytes of raw image data and associated calibration data over the course of the experiment’s run. More than 20 terabytes of data must be stored every night, and annual campaigns to reprocess the entire dataset since the beginning of the survey will be conducted over ten years. The Production and Distributed Analysis (PanDA) system was evaluated by the Rubin Observatory Data Management team and selected to serve the Observatory’s needs due to its demonstrated scalability and flexibility over the years, for its Directed Acyclic Graph (DAG) support, its support for multi-site processing, and its highly scalable complex workflows via the intelligent Data Delivery Service (iDDS). PanDA is also being evaluated for prompt processing where data must be processed within 60 seconds after image capture. This paper will briefly describe the Rubin Data Management system and its Data Facilities (DFs). Finally, it will describe in depth the work performed in order to integrate the PanDA system with the Rubin Observatory to be able to run the Rubin Science Pipelines using PanDA.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

A High-Resolution Integrated Model of the National Ignition Campaign Cryogenic Layered Experiments

A detailed simulation-based model of the June 2011 National Ignition Campaign (NIC) cryogenic DT experiments is presented. The model is based on integrated hohlraum-capsule simulations that utilize the best available models for the hohlraum wall, ablator, and DT equations of state and opacities. The calculated radiation drive was adjusted by changing the input laser power to match the experimentally measured shock speeds, shock merger times, peak implosion velocity, and bangtime. The crossbeam energy transfer model was tuned to match the measured time-dependent symmetry. Mid-mode mix was included by directly modeling the ablator and ice surface perturbations up to mode 60. Simulated experimental values were extracted from the simulation and compared against the experiment. The model adjustments brought much of the simulated data into closer agreement with the experiment, with the notable exception of the measured yields, which were 15-40% of the calculated yields.

42 ENGINEERING↗
DOE OSTI2012

Integrated x-ray reflectivity measurements of elliptically curved pentaerythritol crystals

The elliptically curved pentaerythritol (PET) crystals used in the Supersnout 2 x-ray spectrometer on the National Ignition Facility at Lawrence Livermore National Laboratory have been calibrated photometrically in the range of 5.5-16 keV. The elliptical geometry provides broad spectral coverage and minimizes the degradation of spectral resolution due to the finite source size. The reflectivity curve of the crystals was measured using a x-ray line source. The integrated reflectivity (R{sub I}) and width of its curve ({Delta}{Theta}) were the measurements of major interest. The former gives the spectrometer throughput, and the latter gives the spectrometer resolving power. Both parameters are found to vary considerably with the radius of curvature of the crystal and with spectral energy. The results are attributed to an enhanced mosaic effect due to the increase in curvature. There are also contributions from the crystal cleaving and gluing processes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Catalyst synthesis and evaluation using an integrated atomic layer deposition synthesis–catalysis testing tool

An integrated atomic layer deposition-catalysis (I-ALD-CAT) tool was developed, combining an ALD manifold with a plug-flow reactor system for the synthesis of supported catalytic materials by ALD and immediate evaluation of catalyst reactivity using gas-phase probe reactions. The I-ALD-CAT system can deliver gaseous reagents comprised of 12 different metal ALD precursors, 4 oxidizing or reducing agents, and 4 catalytic reaction feeds to either of the two plug-flow reactors. The system can employ reactor pressures and temperatures in the range of 10 -3 to 1 bar and 300–1000 K, respectively. Furthermore, the instrument is also equipped with a gas chromatograph and a mass spectrometer unit for the detection and quantification of volatile species from ALD and catalytic reactions. In this report, we demonstrate the use of the I-ALD-CAT tool for the ALD of platinum active sites and Al 2 O 3 overcoats, and evaluation of catalyst propylene hydrogenation activity.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Integrating AlGaN/GaN high electron mobility transistor with Si: A comparative study of integration schemes

AlGaN/GaN high electron mobility transistor stacks deposited on a single growth platform are used to compare the most common transition, AlN to GaN, schemes used for integrating GaN with Si. The efficiency of these transitions based on linearly graded, step graded, interlayer, and superlattice schemes on dislocation density reduction, stress management, surface roughness, and eventually mobility of the 2D-gas are evaluated. In a 500 nm GaN probe layer deposited, all of these transitions result in total transmission electron microscopy measured dislocations densities of 1 to 3 × 10{sup 9}/cm{sup 2} and <1 nm surface roughness. The 2-D electron gas channels formed at an AlGaN-1 nm AlN/GaN interface deposited on this GaN probe layer all have mobilities of 1600–1900 cm{sup 2}/V s at a carrier concentration of 0.7–0.9 × 10{sup 13}/cm{sup 2}. Compressive stress and changes in composition in GaN rich regions of the AlN-GaN transition are the most effective at reducing dislocation density. Amongst all the transitions studied the step graded transition is the one that helps to implement this feature of GaN integration in the simplest and most consistent manner.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Integrated modeling of cryogenic layered highfoot experiments at the NIF

Integrated radiation hydrodynamic modeling in two dimensions, including the hohlraum and capsule, of layered cryogenic HighFoot Deuterium-Tritium (DT) implosions on the NIF successfully predicts important data trends. The model consists of a semi-empirical fit to low mode asymmetries and radiation drive multipliers to match shock trajectories, one dimensional inflight radiography, and time of peak neutron production. Application of the model across the HighFoot shot series, over a range of powers, laser energies, laser wavelengths, and target thicknesses predicts the neutron yield to within a factor of two for most shots. The Deuterium-Deuterium ion temperatures and the DT down scattered ratios, ratio of (10–12)/(13–15) MeV neutrons, roughly agree with data at peak fuel velocities <340 km/s and deviate at higher peak velocities, potentially due to flows and neutron scattering differences stemming from 3D or capsule support tent effects. These calculations show a significant amount alpha heating, 1–2.5× for shots where the experimental yield is within a factor of two, which has been achieved by increasing the fuel kinetic energy. This level of alpha heating is consistent with a dynamic hot spot model that is matched to experimental data and as determined from scaling of the yield with peak fuel velocity. Lastly, these calculations also show that low mode asymmetries become more important as the fuel velocity is increased, and that improving these low mode asymmetries can result in an increase in the yield by a factor of several.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗