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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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Computational Icing Analysis on NASA’s SIDRM Geometry to Investigate Collection Efficiency

Computational icing analysis results were compared to experimental icing tunnel data including aerothermal (e.g. dry air) and supercooled water droplet rime-ice conditions from tests conducted in early 2022 at the NASA Icing Research Tunnel (IRT). The Simulated Intercompressor Duct Research Model (SIDRM) test article was used in this study, and its geometry represents the inter-compressor duct region of a turbofan engine. The test article’s purpose is to study the physics of supercooled water icing and ice crystal icing. This study compared three different icing codes: FENSAP-ICE (Eulerian approach), LEWICE3D (Lagrangian approach), and GlennICE (Lagrangian approach). All three icing codes were conducted on SIDRM’s complex body flow-field and compared to different experimental supercooled water rime runs. The test article instrumentation (pressure taps, thermocouples, etc.) and 3D laser scans of final ice shapes were used to compare against the different icing code simulations. The overall objectives are to understand how the icing codes handle capturing collection efficiency on the complex test article’s unheated surfaces. In the aerothermal cases, pressure tap readings matched the CFD results, but dry air CFD underpredicted thermocouple readings. Collection efficiency results from all three icing codes matched well together on the main body leading edge, main body slope, and the strut leading edges. All three icing codes underpredicted the final ice shape using a single-shot constant ice density approach, with more difficulty coming from the strut leading edge ice shape due to the swept wing like flow field. NASA’s overall goal for this effort is to develop computational icing tools to assist in the design and certification of engines for flight in icing conditions.

Supercooled icing, SIDRM, aerodynamics, computatio↗
NASA NTRS1990

Evaluation of discrete frequency sound in closed-test-section wind tunnels

The principal objective of this study is to assess the adequacy of linear acoustic theory with an impedance wall boundary condition for modeling the detailed sound field of an acoustic source in a duct. This study compares measurements and calculations of a simple acoustic source in a rectangular concrete duct lined with foam on the walls and anechoic end terminations. Measuring acoustic pressure for 12 wave numbers provides variation in frequency and absorption characteristics of the duct walls. The cases in this study contain low frequencies and low wall absorptions corresponding to measurements of low-frequency helicopter noise in a lined wind tunnel. This regime is particularly difficult to measure in wind tunnels due to high levels of the reverberant field relatively close to the source. Close to the source, where the interference of wall reflections is minimal, correlation is very good. Away from the source, correlation degrades, especially for the lower frequencies. Sensitivity studies show little effect on the predicted results for changes in impedance boundary condition values, source location, measurement location, temperature, and source model for variations spanning the expected measurement error.

Mosher, Marianne↗
NASA NTRS1991

Terrestrial water storage and polar motion

This study compares observed polar motion for the period 1900-1985 with meteorologic and hydrologic data for the world over the same period, in an effort to determine whether water storage, in combination with air mass redistribution, can account for the observed variance of polar motion. Monthly time series of estimated continental water storage and air mass excitation functions have been compared at the annual frequency and at the Chandler frequency using power, coherence, multiple coherence, and phase spectra. There is a discrepancy in accounting for more than half the variance of polar motion across a broad range of frequencies. Similar results have been obtained in recent studies of polar motion at frequencies above 1 cycle per year using modem space geodetic determinations of polar motion. The persistence of the discrepancey at the annual frequency and its broadband nature suggest a source of polar motion excitation due to air and water motion which has either not been correctly estimated or not yet identified.

Kuehne, John↗
NASA NTRS2002

Performance Analysis of Multilevel Parallel Applications on Shared Memory Architectures

In this paper we describe how to apply powerful performance analysis techniques to understand the behavior of multilevel parallel applications. We use the Paraver/OMPItrace performance analysis system for our study. This system consists of two major components: The OMPItrace dynamic instrumentation mechanism, which allows the tracing of processes and threads and the Paraver graphical user interface for inspection and analyses of the generated traces. We describe how to use the system to conduct a detailed comparative study of a benchmark code implemented in five different programming paradigms applicable for shared memory

Jost, Gabriele↗
DOE OSTI2016

Nuclear binding energy using semi empirical mass formula

In the present communication, semi empirical mass formula using the liquid drop model has been presented. Nuclear binding energies are calculated using semi empirical mass formula with various constants given by different researchers. We also compare these calculated values with experimental data and comparative study for finding suitable constants is added using the error plot. The study is extended to find the more suitable constant to reduce the error.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Management of Sentinel Lymph Node Metastasis in Merkel Cell Carcinoma: Completion Lymphadenectomy, Radiation, or Both?

Background: Approximately 30% of patients with clinically localized Merkel cell carcinoma (MCC) show nodal involvement on sentinel lymph node biopsy (SLNB). Optimal management of SLNB-positive disease has not been defined. This study compared outcomes after completion lymphadenectomy (CLND), radiation, and combined CLND plus radiation after a positive SLNB. Methods: All patients treated at a single institution for SLNB-positive MCC (1998–2015) were retrospectively evaluated, with examination of patient demographics, clinicopathologic characteristics, outcomes, and regional toxicity. Results: The study identified 71 evaluable patients with SLNB-positive disease. The median age of these patients was 76 years, and 76.1% were men. Of the 71 patients, 11 (15.5%) underwent CLND, 40 (56.3%) received radiation, and 20 (28.2%) underwent CLND plus postoperative radiation. Lymphovascular invasion was significantly more common in the radiation-alone cohort (p = 0.04). For the three cohorts, the median percentages of nodal involvement were respectively 2, 10, and 30% (p = 0.06). After a median follow-up period of 22.3 months, four patients had recurrence in their regional nodal basin (3 radiation-alone patients and 1 CLND + radiation patient). The three cohorts did not differ significantly in the development of distant metastases (p = 0.68) or overall survival (p = 0.72). Six patients experienced surgical-site infections (2 CLND and 4 CLND + radiation patients), and three patients experienced symptomatic lymphedema (1 CLND patient and 2 CLND + radiation patients). Conclusions: Regional failure was infrequent (≤ 10%) regardless of treatment, and morbidity appeared to be low with all approaches. Given that multiple treatment approaches can be successful in treating micrometastatic MCC, future efforts should be directed at refining criteria for allocating patients to a specific method, or possibly no further nodal basin treatment, in an effort to maximize regional control at the lowest cost and morbidity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1983

Surface characterization of Ti and Ti (6 percent, Al-4 percent, V) metal powders and interaction with primer solutions

The interaction of Ti and Ti 6-4 powders with water and primer solutions was investigated experimentally by measuring the heats of immersion. Similar comparative studies were made on anatase and rutile TiO2 powders. The surface oxide layers of Ti and Ti 6-4 cracked on heating in vacuum between 300 and 400 C as evidenced by high heats of immersion in both water and primer solutions. Polyimide and polyphenylquinoxaline interacted preferentially, compared with the solvents with both metal powders after outgassing at room temperature. The heats of immersion of Ti 6-4 in water, solvents, and primer solutions increased significantly after pretreatment of the powder by an alkaline etch and a phosphate-fluoride process. The TiO2 powders were not satisfactory models for the surface oxide layer on either Ti or Ti 6-4 powder.

Siriwardane, R. V.↗
DOE OSTI2015

Gold–superheavy-element interaction in diatomics and cluster adducts: A combined four-component Dirac-Kohn-Sham/charge-displacement study

The chemistry of superheavy elements (Z ≥ 104) is actively investigated in atom-at-a-time experiments of volatility through adsorption on gold surfaces. In this context, common guidelines for interpretation based on group trends in the periodic table should be used cautiously, because relativistic effects play a central role and may cause predictions to fall short. In this paper, we present an all-electron four-component Dirac-Kohn-Sham comparative study of the interaction of gold with Cn (Z = 112), Fl (Z = 114), and Uuo (Z = 118) versus their lighter homologues of the 6th period, Hg, Pb, and Rn plus the noble gas Xe. Calculations were carried out for Au–E (E = Hg, Cn, Pb, Fl, Xe, Rn, Uuo), Au{sub 7}– and Au{sub 20}–E (E = Hg, Cn, Pb, Fl, Rn) complexes, where Au{sub 7} (planar) and Au{sub 20} (pyramidal) are experimentally determined clusters having structures of increasing complexity. Results are analysed both in terms of the energetics of the complexes and of the electron charge rearrangement accompanying their formation. In line with the available experimental data, Cn and more markedly Fl are found to be less reactive than their lighter homologues. On the contrary, Uuo is found to be more reactive than Rn and Xe. Cn forms the weakest bond with the gold atom, compared to Fl and Uuo. The reactivity of Fl decreases with increasing gold-fragment size more rapidly than that of Cn and, as a consequence, the order of the reactivity of these two elements is inverted upon reaching the Au{sub 20}-cluster adduct. Density difference maps between adducts and fragments reveal similarities in the behaviour of Cn and Xe, and in that of Uuo and the more reactive species Hg and Pb. These findings are given a quantitative ground via charge-displacement analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Impact of Radical Hysterectomy Versus Simple Hysterectomy on Survival of Patients with Stage 2 Endometrial Cancer: A Meta-analysis

Background: The strategy of radical surgery for stage 2 endometrial cancer (EC) remains controversial. This meta-analysis aimed to investigate the impact of radical hysterectomy (RH) versus simple hysterectomy (SH) on survival of patients with stage 2 EC. Methods: A systematic review was conducted to identify studies comparing survival between RH and SH in International Federation of Gynecology and Obstetrics (FIGO) stage 2 EC patients by searching several databases to July 2018. Hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival and progression-free survival were pooled using Stata V.12.0. Results: The study included 10 retrospective cohort studies enrolling 2866 patients. Patients who received RH did not show a significant survival benefit for either overall survival (pooled HR 0.92; 95% CI 0.72–1.16; P = 0.484) or progression-free survival (pooled HR 0.75; 95% CI 0.39–1.42; P = 0.378). The result remained consistent after it was balanced with possible impact from adjuvant radiotherapy (pooled HR 0.85; 95% CI 0.62–1.16; P = 0.300). In earlier studies that staged patients according to FIGO 1988, RH showed a 27% survival benefit (pooled HR 0.73; 95% CI 0.53–1.00; P = 0.050), whereas in newly published studies based on FIGO 2009 staging, it reversely showed increased risk of death (pooled HR 1.24; 95% CI 0.86–1.77; P = 0.245). However, no statistical significance was reached under either staging criterion. Conclusions: Based on the results of this meta-analysis, RH does not significantly improve survival in stage 2 EC. The choice of RH remains controversial and should be considered carefully in clinical practice. More qualified studies are needed to determine the best treatment strategy for stage 2 EC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Comparison of Electromagnetic Transient and Phasor-based Simulation for the Stability of Grid-Forming-Inverter-based Microgrids

The increasing interest in studying feeder-level, inverter-based microgrids requires appropriate simulation methods that can effectively simulate the dynamics of distribution feeders that typically have thousands of nodes. To examine the accuracy of phasor-based simulation for the stability of feeder-level, inverter-based microgrids, a comparative study between electromagnetic transient (EMT) and phasor-based simulation was conducted. Case studies of a two-inverter small microgrid and a modified version of the IEEE 34-Node Test System that has seven grid-forming inverters show that phasor-based simulation agrees well with EMT simulation when the P-f droop gains of grid-forming inverter controllers are within normal ranges. However, under extremely high P-f droop gains, phasor-based simulation can result in over-optimistic stability results. This study provides insight into the applicability of phasor-based simulation for the stability of feeder-level, inverter-based microgrids.

Du, Wei↗
DOE OSTI2021

Enhancing membrane performance for CO 2 capture from flue gas with ultrahigh MW polyvinylamine

Membranes for post-combustion CO 2 capture are required to have a high CO 2 permeance due to the limited driving force. For facilitated transport membranes synthesized with polyvinylamine (PVAm), a defect-free selective layer of <200 nm is usually required to render sufficient permeance with high CO 2 /N 2 selectivity. In order to meet such a demand through the knife-coating process, the coating solution needs to have a high viscosity at a relatively low concentration to minimize its penetration into the substrate. The demand was met by synthesizing PVAm with an ultrahigh molecular weight (MW) via inverse emulsion polymerization (IEP) in this study. Compared to solution polymerization, IEP isolates the reaction in inverse micelles suspended in a continuous organic phase, which allows excellent dissipation of the heat generated by the reaction and reduces gel formation drastically. The polymerization parameters, including monomer concentration, initiator concentration, and reaction temperature, were investigated to obtain the optimal MW of PVAm for membrane performance. As compared to solution polymerization, IEP enhanced the MW of PVAm from 1.2 to 12.7 MDa, which minimized the penetration of the coating solution into the substrate and hence the extra mass transfer resistance. The effect of MW and degree of hydrolysis of PVAm on the membrane transport properties were studied. Furthermore, by employing PVAm with a MW of 12.7 MDa to strengthen the polymer matrix, the loading of piperazine glycinate in the membrane was increased up to 85 wt.%. In conclusion, the resultant membrane achieved a CO 2 permeance of 839 GPU and a CO 2 /N 2 selectivity of 161 at the typical flue gas temperature of 57°C.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2016

Rejoinder

We are grateful for the many insightful comments provided by the discussants. One team politely pointed out oversights in our literature review and the subsequent omission of a formidable comparator. Another made an important clarification about when a more aggressive variation (the so-called NoMax) would perform poorly. A third team offered enhancements to the framework, including a derivation of closed-form expressions and a more aggressive updating scheme; these enhancements were supported by an empirical study comparing new alternatives with old. The last team suggested hybridizing the statistical augmented Lagrangian (AL) method with modern stochastic search. Here we present our responses to these contributions and detail some improvements made to our own implementations in light of them. We conclude with some thoughts on statistical optimization using surrogate modeling and open-source software.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Frequency-dependent dielectric function of semiconductors with application to physisorption

Furthermore, the dielectric function is one of the most important quantities that describes the electrical and optical properties of solids. Accurate modeling of the frequency-dependent dielectric function has great significance in the study of the long-range van der Waals (vdW) interaction for solids and adsorption. In this work we calculate the frequency-dependent dielectric functions of semiconductors and insulators using the GW method with and without exciton effects, as well as efficient semilocal density functional theory (DFT), and compare these calculations with a model frequency-dependent dielectric function. We find that for semiconductors with moderate band gaps, the model dielectric functions, GW values, and DFT calculations all agree well with each other. However, for insulators with strong exciton effects, the model dielectric functions have a better agreement with accurate GW values than the DFT calculations, particularly in high-frequency region. To understand this, we repeat the DFT calculations with scissors correction, by shifting the DFT Kohn-Sham energy levels to match the experimental band gap. We find that scissors correction only moderately improves the DFT dielectric function in the low-frequency region. Based on the dielectric functions calculated with different methods, we make a comparative study by applying these dielectric functions to calculate the vdW coefficients (C3 and C5) for adsorption of rare-gas atoms on a variety of surfaces. We find that the vdW coefficients obtained with the nearly free electron gas-based model dielectric function agree quite well with those obtained from the GW dielectric function, in particular for adsorption on semiconductors, leading to an overall error of less than 7% for C 3 and 5% for C 5 . This demonstrates the reliability of the model dielectric function for the study of physisorption.

36 MATERIALS SCIENCE↗
DOE OSTI2016

SU-F-E-13: Design and Fabrication of Gynacological Brachytherapy Shielding & Non Shielding Applicators Using Indigenously Developed 3D Printing Machine

Purpose: In this innovative work we have developed Gynecological Brachytherapy shielding & Non Shielding Applicators and compared with the commercially available applicators by using the indigenously developed 3D Printing machine. Methods: We have successfully indigenously developed the 3D printing machine. Which contain the 3 dimensional motion platform, Heater unit, base plate, ect… To fabricate the Gynecological Brachytherapy shielding & non shielding applicators the 3D design were developed in the computer as virtual design. This virtual design is made in a CAD computer file using a 3D modeling program. Separate programme for the shielding & non shielding applicators. We have also provided the extra catheter insert provision in the applicator for the multiple catheter. The DICOM file of the applicator were then converted to stereo Lithography file for the 3D printer. The shielding & Non Shielding Applicators were printed on a indigenously developed 3D printer material. The same dimensions were used to develop the applicators in the acrylic material also for the comparative study. A CT scan was performed to establish an infill-density calibration curve as well as characterize the quality of the print such as uniformity and the infill pattern. To commission the process, basic CT and dose properties of the printing materials were measured in photon beams and compared against water and soft tissue. Applicator were then scanned to confirm the placement of multiple catheter position. Finally dose distributions with rescanned CTs were compared with those computer-generated applicators. Results: The doses measured from the ion Chamber and X-Omat film test were within 2%. The shielded applicator reduce the rectal dose comparatively with the non shielded applicator. Conclusion: As of submission 3 unique cylinders have been designed, printed, and tested dosimetrically. A standardizable workflow for commissioning custom 3D printed applicators was codified and will be reported.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SciDAC Center for Simulation of Wave-Plasma Interactions - Iterated Finite-Orbit Monte Carlo Simulations with Full-Wave Fields for Modeling Tokamak ICRF Wave Heating Experiments - Final Report

This final report describes the work performed under U.S. Department of Energy Cooperative Agreement DE-FC02-08ER54954 for the period April 1, 2011 through March 31, 2013. The goal of this project was to perform iterated finite-orbit Monte Carlo simulations with full-wall fields for modeling tokamak ICRF wave heating experiments. In year 1, the finite-orbit Monte-Carlo code ORBIT-RF and its iteration algorithms with the full-wave code AORSA were improved to enable systematical study of the factors responsible for the discrepancy in the simulated and the measured fast-ion FIDA signals in the DIII-D and NSTX ICRF fast-wave (FW) experiments. In year 2, ORBIT-RF was coupled to the TORIC full-wave code for a comparative study of ORBIT-RF/TORIC and ORBIT-RF/AORSA results in FW experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Exploring the Use of FHWA Truck Traffic Volume and Weight Data to Support National Truck Freight Mobility Study

The goal of this exploratory study was to investigate alternative data sources and develop methodologies to estimate trends and adjustment factors that could be applied to calibrate statistics generated from the outdated 2002 VIUS. The main focus of this study was on utilizing the FHWA’s traffic data (i.e., VTRIS and TMAS), along with other supplemental freight data (i.e., FAF and CFS), to examine changes in truck volumes and truck weight distributions over time. Ultimately, this effort seeks to develop certain adjustments/factors that could be used to realign perspective VIUS data. Unfortunately, as pointed out previously in this technical memorandum, there are no readily available data sources that could be used to explicitly validate the estimated results from this study. This study compared the estimated distributions from the 2002 VTRIS to the 2002 VIUS data to establish linkages between the two datasets. With distributions and patterns generated based on VTRIS and TMAS data series for additional years, trend factors were then estimated and applied to “update” VIUS-based information. This study resulted in three key highlights: (1) Updated estimates on truck volume and truck VMT can be utilized to better estimate on energy uses by truck. (2) Vehicle class distribution, percent/share of empty trucks, and average truck payload could be updated by utilizing more current annual data series such as VTRIS and TMAS. (3) Additional information could be estimated (e.g., distance distribution by operational type) by integrating other data sources, such as CFS and FAF, instead of relying on the 2002 VIUS data.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2018

Nb3Sn Multilayer Sequential Sputtering at Jefferson Lab

Nb3Sn-coated Nb SRF cavities are studied due to their potential of providing a higher accelerating gradient over Nb SRF cavities. Magnetron sputtering can be a feasible alternative to conventional tin vapor diffusion process to fabricate Nb3Sn for SRF cavities. By depositing Nb and Sn layers separately and annealing afterwards, the stoichiometry of the coated films can be controlled to create Nb3Sn. To understand the formation of Nb3Sn at higher annealing temperatures, a comparative study of deposition and processing conditions is required. We have sputtered Nb and Sn multilayers and post-deposition annealed at 850, 950, 1000, 1100 and 1200 °C for 3 hours. The structural properties of the annealed films were characterized by X-ray diffraction (XRD) and compared to as-coated films. The film microstructures and compositions were examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The superconducting transition of the films were measured by surface resistivity data obtained down to cryogenic temperatures. A new cavity deposition system with a cylindrical magnetron has been designed to implement the sequential sputtering technique onto a single-cell cavity.

Eremeev, Grigory↗